U.S. patent application number 11/057544 was filed with the patent office on 2005-07-07 for methods and apparatus for anchoring an occluding member.
Invention is credited to Fan, Sylvia W., Mueller, Richard L. JR., Snow, David W., Valley, Kirsten L..
Application Number | 20050148997 11/057544 |
Document ID | / |
Family ID | 24279021 |
Filed Date | 2005-07-07 |
United States Patent
Application |
20050148997 |
Kind Code |
A1 |
Valley, Kirsten L. ; et
al. |
July 7, 2005 |
Methods and apparatus for anchoring an occluding member
Abstract
Pressure is measured on both sides of an occluding member for
determining when pressure forces on the occluding member may cause
migration of the occluding member. An alarm indicates when the
pressure force on the balloon exceed a predetermined threshold. In
another aspect of the invention, a pressure monitor determines when
a rate of pressure increase with respect to the fluid volume in the
balloon reaches a predetermined threshold when inflating the
occluding member. A predetermined amount of fluid is then added to
the balloon so that the balloon is not under inflated or over
inflated.
Inventors: |
Valley, Kirsten L.;
(Mountain View, CA) ; Snow, David W.; (Woodside,
CA) ; Fan, Sylvia W.; (San Francisco, CA) ;
Mueller, Richard L. JR.; (Byron, CA) |
Correspondence
Address: |
PHILIP S. JOHNSON
JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
24279021 |
Appl. No.: |
11/057544 |
Filed: |
February 14, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11057544 |
Feb 14, 2005 |
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09759431 |
Jan 12, 2001 |
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09759431 |
Jan 12, 2001 |
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09114307 |
Jul 13, 1998 |
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6251093 |
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09114307 |
Jul 13, 1998 |
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08570286 |
Dec 11, 1995 |
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5795325 |
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08570286 |
Dec 11, 1995 |
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08486216 |
Jun 7, 1995 |
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5766151 |
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08486216 |
Jun 7, 1995 |
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08282192 |
Jul 28, 1994 |
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5584803 |
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08282192 |
Jul 28, 1994 |
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08162742 |
Dec 3, 1993 |
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08162742 |
Dec 3, 1993 |
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08123411 |
Sep 17, 1993 |
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08123411 |
Sep 17, 1993 |
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07991188 |
Dec 15, 1992 |
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07991188 |
Dec 15, 1992 |
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07730559 |
Jul 16, 1991 |
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5370685 |
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Current U.S.
Class: |
604/509 ;
604/96.01 |
Current CPC
Class: |
A61M 25/0155 20130101;
A61M 2202/047 20130101; A61M 2025/1077 20130101; A61M 2205/366
20130101; A61M 2210/127 20130101; A61M 1/3659 20140204; A61B
2090/064 20160201; A61M 2025/0031 20130101; A61B 2018/00261
20130101; A61M 2025/0046 20130101; A61M 2025/015 20130101; A61M
2025/1095 20130101; A61M 25/0147 20130101; A61M 2025/1059 20130101;
A61F 2/2427 20130101; A61M 2210/125 20130101; A61M 25/0662
20130101; A61M 25/02 20130101; A61B 17/12045 20130101; A61M 25/0152
20130101; A61B 2018/00232 20130101; A61M 2025/1047 20130101; A61M
1/3653 20130101; A61M 25/1029 20130101; A61M 25/0032 20130101; A61M
2025/0161 20130101; A61B 17/12036 20130101; A61M 25/1034 20130101;
A61B 2017/00243 20130101; A61M 2025/0034 20130101; A61M 2025/1052
20130101; A61M 2025/0078 20130101; A61M 1/3613 20140204; A61M
2025/0002 20130101; A61B 17/12022 20130101; A61M 2025/028 20130101;
A61M 25/0041 20130101; A61M 25/0125 20130101; A61B 17/12136
20130101; A61M 25/10 20130101; A61M 25/0054 20130101; A61M
2025/1031 20130101; A61M 25/0028 20130101; A61M 25/1027 20130101;
A61M 2205/11 20130101; A61M 25/1002 20130101; A61B 2090/306
20160201; A61M 25/1006 20130101; A61B 17/12109 20130101 |
Class at
Publication: |
604/509 ;
604/096.01 |
International
Class: |
A61M 029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 1992 |
AU |
PL 6170 |
Claims
What is claimed is:
1. A method of anchoring a balloon catheter in a patient,
comprising the steps of: positioning the balloon in the patient's
body passageway with the balloon in the collapsed shape so that the
radially outward extremes contact the body passageway; and
advancing the balloon in the patient to a position to be occluded
with the balloon in the collapsed shape; inflating the balloon
after the advancing step so that the high friction portion contacts
the patient's body passageway for anchoring the balloon in the
patient's body passageway.
2. The method of claim 1, wherein: the positioning step is carried
out by inserting the balloon into the patient's arterial system;
and the inflating step is carried out with the balloon being
positioned in the patient's ascending aorta.
3. The method of claim 1, wherein: the providing step is carried
out with the balloon catheter having a first lumen and an opening
at the distal end fluidly coupled to the first lumen, the opening
being configured for delivery of a fluid into a patient,
4. The method of claim 3, further comprising the step of:
introducing cardioplegic fluid into the patient through the first
lumen.
5. The method of claim 1, wherein: the providing step is carried
out with the balloon catheter having at least three arms extending
radially outward from the shaft.
6. The method of claim 1, wherein: the providing step is carried
out with the high friction portion having a plurality of ribs.
7. The method of claim 1, wherein: the providing step is carried
out with the shaft having a substantially straight portion and a
hooked portion connected to the substantially straight portion.
8. A balloon catheter for occluding a body passageway in a patient,
comprising: a shaft; and a balloon mounted to the shaft, the
balloon having an expanded shape and a collapsed shape, the
expanded shape being configured to occlude a body passageway in a
patient, the balloon including an outer surface having at least two
high friction portions and a low friction portion, the low friction
portion having a lower coefficient of friction than the high
friction portions relative to the patient's body passageway, the
balloon having at least three radially extending arms when in the
collapsed shape, each of the at least two low friction portions
being positioned at radially outward extremes of adjacent radially
extending arms, the high friction portion being exposed and being
positioned between two of the radially outward extremes of the
radially extending arms when the balloon is in the collapsed shape,
the high friction portion being everted when the balloon moves from
the collapsed shape to the expanded shape.
9. The balloon catheter of claim 8, wherein: the balloon is
configured and sized to occlude the patient's ascending aorta.
10. The balloon catheter of claim 8, wherein: the shaft includes a
first lumen and an opening at the distal end fluidly coupled to the
first lumen, the opening being configured for delivery of a fluid
into a patient.
11. The balloon catheter of claim 8, further comprising: a source
of cardioplegic fluid fluidly coupled to the first lumen.
12. The balloon catheter of claim 8, wherein: the high friction
portion includes a plurality of ribs.
13. The balloon catheter of claim 8, wherein: the shaft has a
substantially straight portion and a hooked portion connected to
the substantially straight portion.
14. A method for positioning a balloon in a passageway and
occluding the passageway, comprising the steps of: providing a
catheter having a shaft and a balloon mounted thereto, the balloon
having a collapsed shape and an expanded shape; inserting the
catheter into a body passageway of a patient with the balloon in
the collapsed shape; positioning the catheter in a portion of the
body passageway for occluding the portion of the body passageway;
inflating the balloon with a fluid; monitoring a rate of pressure
increase in the balloon with respect to a fluid volume in the
balloon; and adding an amount of fluid after the rate of pressure
increase in the balloon exceeds a predetermined threshold.
15. The method of claim 14, wherein: the positioning step is
carried out by positioning the balloon in the patient's ascending
aorta.
16. The method of claim 14, wherein: the providing step is carried
out with the catheter having a lumen fluidly coupled to the
balloon, the catheter also having a pressure sensor and a pressure
sensing alarm, the pressure sensing alarm indicating when the rate
of pressure increase in the balloon exceeds the predetermined
threshold.
17. The method of claim 14, wherein: the adding step is carried out
with the amount of fluid being a predetermined volume of fluid.
18. The method of claim 14, wherein: the adding step is carried out
by adding the amount of fluid to increase the pressure in the
balloon a predetermined amount.
19. A device for pressurizing a balloon catheter, comprising: a
catheter having a shaft and a balloon mounted thereto, the balloon
having a collapsed shape and an expanded shape, the collapsed shape
being configured for advancement within a patient the catheter
having a first lumen fluidly coupled to the balloon for inflating
the balloon; a fluid source coupled to the first lumen for
inflating the balloon; a pressure sensor configured to measure a
pressure in an interior of the balloon; and a pressure monitor
coupled to the pressure sensor, the pressure monitor determining
when a rate of pressure increase in the balloon with respect to an
increase in fluid volume in the balloon exceeds a predetermined
threshold.
20. The device of claim 19, further comprising: means for adding a
predetermined amount of fluid after the pressure monitor detects
the rate of pressure increase exceeds the predetermined
threshold.
21. The device of claim 19, further comprising: means for
increasing the pressure in the balloon a predetermined amount after
the pressure monitor detects the rate of pressure increase exceeds
the predetermined threshold.
22. A method of anchoring an occluding member in a patient,
comprising the steps of: inserting a catheter having an occluding
member mounted thereto, the occluding member having a collapsed
shape and an expanded shape; positioning the occluding member in a
body passageway in the patient; expanding the occluding member to
the expanded shape after the positioning step to thereby occlude
the body passageway; monitoring a pressure exerted on the occluding
member on a distal side and a proximal side of the occluding
member; and determining a difference between the pressure on the
distal and proximal sides of the occluding member.
23. The method of claim 22, further comprising the step of:
adjusting a pressure on at least one of the distal and proximal
sides of the occluding member.
24. The method of claim 22, wherein: the adjusting step is carried
out by adjusting a pressure on the distal side of the occluding
member.
25. The method of claim 22, wherein: the inserting step is carried
out with the occluding member being a balloon.
26. The method of claim 22, wherein: the inserting step is carried
out with the body passageway being an ascending aorta.
27. A catheter for occluding an ascending aorta in a patient,
comprising: a shaft having a distal end and a proximal end; an
occluding member mounted to the shaft, the occluding member having
an expanded shape sized to occlude the patient's ascending aorta; a
first pressure sensor positioned between the distal end and the
occluding member for measuring a pressure on a first side of the
occluding member; and a second pressure sensor positioned between
the proximal end and the occluding for measuring a pressure on a
second side of the occluding member.
28. The catheter of claim 27, further comprising: a pressure
monitor coupled to the first and second pressure sensors, the
pressure monitor determining a pressure difference between the
first and second pressure sensors.
29. The catheter of claim 28, further comprising: an alarm coupled
to the pressure monitor for indicating when a pressure difference
sensed by the first and second pressure sensors exceeds a
predetermined threshold.
30. The catheter of claim 27, wherein: the occluding member is a
balloon; and the shaft includes a first lumen, a second lumen and
an opening at the distal end of the shaft fluidly coupled to the
first lumen, the second lumen being fluidly coupled to the balloon
for inflating the balloon.
31. The catheter of claim 30, further comprising: means for
adjusting the pressure on at least one of the first and second
sides of the balloon when a pressure difference sensed by the first
and second pressure sensors exceeds a predetermined threshold, the
pressure adjusting means reducing the pressure difference to a
value below the predetermined threshold.
32. The catheter of claim 31, wherein: the pressure adjusting means
is coupled to the first lumen for adjusting a fluid pressure
exerted by fluid delivered into the ascending aorta through the
first lumen.
33. A method of anchoring an occluding member in an ascending aorta
of a patient, comprising the steps of: inserting a catheter into a
patient, the catheter including a shaft having an occluding member
at a distal end, the occluding member having a collapsed shape and
an expanded shape; positioning the catheter in the patient's
ascending aorta; expanding the occluding member to the expanded
shape after the positioning step to thereby occlude the ascending
aorta; and displacing the shaft of the catheter a first amount
after the expanding step so that a predetermined portion of the
catheter contacts the patient's aortic lumen for anchoring the
occluding member in the ascending aorta.
34. The method of claim 33, wherein: the displacing step is carried
out by withdrawing an amount of the catheter from the patient so
that the predetermined portion of the catheter engages a radially
inner portion of the patient's ascending aorta.
35. The method of claim 33, further comprising the step of:
displacing the catheter a second amount in a direction opposite to
the first amount so that a second predetermined portion of the
shaft engages a radially outer wall of the patient's ascending
aorta.
36. The method of claim 33, further comprising the step of:
inserting the shaft through a delivery cannula, the delivery
cannula having a shaft engaging mechanism and a shaft displacing
mechanism; the displacing step being performed with the shaft
displacing mechanism of the delivery cannula.
37. A catheter having an expandable member for occluding an
ascending aorta in a patient, comprising: a shaft having a
longitudinal axis, a distal end, a proximal end, a first lumen and
an opening at the distal end in fluid communication with the
opening, the opening being configured for delivery of a fluid into
the patient's ascending aorta; an expandable member mounted near
the distal end of the shaft, the expandable member having an
expanded shape and a collapsed shape, the expanded shape being
configured to occlude the patient's ascending aorta; and a delivery
cannula, the shaft being movably coupled to the delivery cannula
for movement in a direction parallel to the longitudinal axis in an
inward direction and an outward direction; the shaft having a first
portion configured to contact the radially inner wall of the aortic
lumen when the shaft is slidably displaced in the outward
direction.
38. The catheter of claim 37, further comprising: a shaft
displacing mechanism coupled to the delivery cannula, the shaft
displacing mechanism being configured to displace the shaft a
predetermined amount in the outward direction so that the first
portion engages the radially inner wall of the aortic lumen.
39. The catheter of claim 37, wherein: the shaft includes a second
portion configured to contact a radially outer wall of the aortic
lumen when the shaft is slidably displaced in the inward
direction.
40. The catheter of claim 39, wherein: the shaft includes a third
portion configured to contact the radially outer wall of the aortic
lumen when the shaft is slidably displaced in the inward direction,
the second portion being positioned between the first and second
portions.
41. The catheter of claim 37, wherein: the delivery cannula
includes a lumen for introducing a fluid into the patient.
42. The catheter of claim 37, wherein: the shaft includes a first
bend and a second bend, the first portion being positioned between
the first and second bends.
43. A method of anchoring an occluding member in a patient
comprising the steps of: inserting a catheter into a patient, the
catheter having an occluding member mounted thereto; positioning
the occluding member at a desired location; expanding the occluding
member to occlude the desired location; and clamping a portion of
the passageway adjacent the desired location to prevent migration
of the occluding member.
44. The method of claim 43, wherein: the inserting step is carried
out with the occluding member being a balloon.
45. The method of claim 43, wherein: the clamping step is carried
out by clamping the body passageway around the balloon thereby
trapping the balloon.
46. The method of claim 43, wherein: the inserting step is carried
out with the balloon having an indentation; and the clamping step
is carried out with the clamp being positioned around the
indentation.
47. A method of anchoring an occluding member in a patient's
ascending aorta comprising the steps of: inserting an occluding
member in the ascending aorta between the coronary ostia and the
brachiocephalic artery; expanding the occluding member in the
patient after the inserting step; positioning an anchor in the
brachiocephalic artery, the anchor having a proximal end extending
into the aorta, the anchor preventing migration of the occluding
member beyond the brachiocephalic artery.
48. The method of claim 47, wherein: the positioning step is
carried out with the anchor being a perfusion catheter configured
to deliver oxygenated blood to the brachiocephalic artery.
49. The method of claim 47, wherein: the anchor is separate from
the catheter.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 08/570,286, filed Dec. 11, 1995, which is a
continuation-in-part of Ser. No. 08/486,216, filed Jun. 7, 1995
which is a continuation-in-part of application of copending U.S.
patent application Ser. No. 08/282,192, filed Jul. 28, 1994, which
is a continuation-in-part of application Ser. No. 08/162,742, filed
Dec. 3, 1993, which is a continuation-in-part of application Ser.
No. 08/123,411, filed Sep. 17, 1993, which is a
continuation-in-part of application Ser. No. 07/991,188, filed Dec.
15, 1992, which is a continuation-in-part of application Ser. No.
07/730,559, filed Jul. 16, 1991, which issued as U.S. Pat. No.
5,370,685 on Dec. 6, 1994. This application is also related to
copending U.S. patent application Ser. No. 08/159,815, filed Nov.
30, 1993, which is a U.S. counterpart of Australian Patent
Application No. PL 6170, filed Dec. 3, 1992. This application is
also related to copending U.S. patent application Ser. No. 08/281,
962, filed Jul. 28, 1994, which is a continuation-in-part of
application Ser. No. 08/163,241, filed Dec. 6, 1993, which is a
continuation-in-part of application Ser. No. 08/023,778, filed Feb.
22, 1993. This application is also related to copending U.S. patent
application Ser. No. 08/281,981, filed Jul. 28, 1994, which is a
continuation-in-part of application Ser. No. 08/023,778, filed Feb.
22, 1993. This application is also related to copending U.S. patent
application Ser. No. 08/213,760, filed Mar. 16, 1994. The complete
disclosures of all of the aforementioned related U.S. patent
applications are hereby incorporated herein by reference for all
purposes.
FIELD OF THE INVENTION
[0002] The present invention is directed to apparatus and methods
for reducing migration of occlusion members. A specific application
of the invention is described in conjunction with devices and
methods for temporarily inducing cardioplegic arrest in the heart
of a patient and for establishing cardiopulmonary bypass in order
to facilitate surgical procedures on the heart and blood
vessels.
BACKGROUND OF THE INVENTION
[0003] Various cardiovascular, neurosurgical, pulmonary and other
interventional procedures, including repair or replacement of
aortic, mitral and other heart valves, repair of septal defects,
congenital defect repairs, pulmonary thrombectomy, coronary artery
bypass grafting, angioplasty, atherectomy, treatment of aneurysms,
electrophysiological mapping and ablation, and neurovascular
procedures, may require general anesthesia, cardiopulmonary bypass,
and arrest of cardiac function. In such procedures, the heart and
coronary blood vessels are isolated from the remainder of the
circulatory system. This serves several purposes. First, such
isolation facilitates infusion of cardioplegic fluid into the
coronary arteries to perfuse the myocardium and arrest cardiac
function without allowing the cardioplegic fluid to be distributed
elsewhere in the patient's circulatory system. Second, such
isolation facilitates use of a cardiopulmonary bypass system to
maintain circulation of oxygenated blood throughout the circulatory
system without allowing such blood to reach the coronary arteries
and resuscitate the heart. Third, in cardiac procedures, such
isolation creates a working space into which the flow of blood and
other fluids can be controlled or prevented so as to create an
optimum surgical environment.
[0004] One medical procedure of particular interest to the present
invention is the treatment of heart valve disease. Co-owned,
copending patent application Ser. No. 08/281, 962 and Ser. No.
08/486,216, which are incorporated herein by reference, describe
methods of performing closed-chest or thoracoscopic heart valve
replacement surgery. Isolating the heart from the systemic blood
circulation, inducing cardioplegic arrest and establishing
cardiopulmonary bypass are important steps in the performance of
the heart valve replacement procedure.
[0005] The endovascular system includes an elongated aortic
partitioning catheter having an occluding member on a distal
portion of the catheter adapted to occlude a patient's ascending
aorta. The catheter preferably has an inner lumen extending within
the catheter to a port in the distal end of the catheter. The
catheter is adapted to be inserted into the patient's arterial
system (e.g. through the femoral or brachial arteries) and advanced
to the ascending aorta where the occluding member is expanded to
occlude the aorta. The occluding member separates the left
ventricle of the heart and an upstream portion of the ascending
aorta from the rest of the patient's arterial system. Thus, the
catheter provides an endovascularly inserted, internal vascular
clamp, similar in function to the external "cross-clamp" used in
open cardiac surgical procedures. The internal clamp is less
traumatic to the clamped vessel and provides a lumen or working
channel through which instruments or fluids may be passed into or
withdrawn from the area upstream of the distal end of the
clamp.
[0006] Also included with the system is a cardiopulmonary bypass
system which withdraws blood from the patient's venous system, e.g.
the femoral or jugular vein, removes CO.sub.2 and adds oxygen to
the withdrawn blood, and returns the oxygenated blood to the
patient's arterial system, e.g. the femoral or brachial artery. The
system is also provided with a device for infusing fluid containing
cardioplegic material (e.g. an aqueous solution of KCl and/or
magnesium procaine and the like) through the coronary arteries so
as to temporarily paralyze the myocardium.
[0007] A preferred method for inducing cardioplegic arrest of a
heart in situ in a patient's body, includes the steps of:
[0008] (a) maintaining systemic circulation with peripheral
cardiopulmonary bypass;
[0009] (b) partitioning the coronary arteries from the ascending
aorta by, e.g., occluding the ascending aorta through a
percutaneously placed arterial balloon catheter;
[0010] (c) introducing a cardioplegic agent into the coronary
circulation; and
[0011] (d) venting the heart.
[0012] The method may be carried out on humans or other mammalian
animals. The method is of particular applicability in humans as it
allows an alternative approach to open heart surgery and the
development of closed cardioscopic surgery. The method enables a
percutaneous bypass system to be associated with cardioplegia,
venting and cooling of the heart which overcomes the need for a
median sternotomy.
[0013] In a preferred embodiment, the occluding member is an
inflatable cuff or balloon of sufficient size to occlude the
ascending aorta. The length of the balloon should preferably not be
so long as to impede the flow of blood or other solution to the
coronary arteries or to the brachiocephalic, left carotid or left
subclavian arteries. A balloon length of about 20-40 mm and
diameter of about 35 mm is suitable in humans. The balloon may be
cylindrical, spherical, ellipsoidal or any other appropriate shape
to fully and evenly accommodate the lumen of the ascending aorta.
This maximizes the surface area contact with the aorta, and allows
for even distribution of occlusive pressure.
[0014] The balloon is preferably inflated with a saline solution
mixed with a radiopaque contrast agent to avoid introducing an air
embolism if the balloon ruptures. The balloon should be inflated to
a pressure sufficient to prevent regurgitation of blood into the
aortic root and to prevent migration of the balloon into the root
whilst not being so high as to damage the aorta. An intermediate
pressure of about 350 mm Hg, for example, is preferred.
[0015] The aortic partitioning catheter is preferably introduced
under fluoroscopic guidance over a guidewire. Transoesophageal
echocardiography can also be used for positioning the aortic
catheter. The catheter may serve a number of separate functions and
the number of lumina in the catheter will depend upon how many of
those functions the catheter is to serve. The catheter can be used
to introduce the cardioplegic agent, normally in solution, into the
aortic root via one lumen. The luminal diameter will preferably be
such that a flow of the order of 100-500 ml/min of cardioplegic
solution, and more preferably 250-500 ml/min, can be introduced
into the aortic root under positive pressure to perfuse the heart
by way of the coronary arteries. The same lumen can, by applying
negative pressure to the lumen from an outside source, effectively
vent the left heart of blood or other solutions. The cardioplegic
agent may be any known cardioplegic agent. The agent is preferably
infused as a solution into the aortic root through one of the
lumina of the aortic catheter.
[0016] It may also be desirable to introduce medical instruments
and/or a cardioscope into the heart through another lumen in the
catheter. The lumen should be of a diameter suitable to pass a
fiberoptic light camera of no greater than 3 mm diameter. It is,
however, preferable that the diameter and cross-section of the
internal lumina are such that the external diameter of the catheter
is small enough for introduction into the adult femoral artery by
either percutaneous puncture or direct cutdown.
[0017] The oxygenated blood returning to the body from the bypass
system is conveyed into the aorta from another lumen in the cannula
carrying the balloon. In this case, the returning blood is
preferably discarded from the catheter in the external iliac
artery. In another embodiment of the invention, and in order to
reduce the diameter of the catheter carrying the balloon, a
separate arterial catheter of known type may be used to return
blood to the patient from the bypass system. In this case a short
catheter is positioned in the other femoral artery to provide
systemic arterial blood from the bypass system. The control end of
the catheter, i.e. the end that remains outside the body, should
have separate ports of attachment for the lumina. The catheter
length should be approximately 900 mm for use in humans.
[0018] With the heart paralyzed, the expandable member is expanded
within the ascending aorta, and with the cardiopulmonary bypass
operating, the heart is prepared for a cardiac procedure. While a
particularly attractive feature of the invention is that it
prepares the heart for endovascular, thoracoscopic, and other
minimally-invasive procedures, the invention can also be used to
prepare the heart for conventional open-heart surgery via a
thoracotomy. It should also be noted that, if during an
endovascular cardiac procedure in accordance with the invention, it
becomes necessary to perform an open-heart procedure, the patient
is already fully prepared for the open-heart procedure. All that is
necessary is to perform a median sternotomy to expose the patient's
heart for the conventional surgical procedure.
[0019] The endovascular device for partitioning the ascending aorta
between the coronary ostia and the brachiocephalic artery
preferably includes a flexible shaft having a distal end, a
proximal end, and a first lumen therebetween with an opening at the
distal end in communication with the first lumen. The shaft has a
distal portion which is shaped for positioning in the aortic arch
so that the distal end is disposed in the ascending aorta pointing
toward the aortic valve. The first lumen may be used to withdraw
blood or other fluids from the ascending aorta, to introduce
cardioplegic fluid into the coronary arteries for paralyzing the
myocardium, and/or to introduce, surgical instruments into the
ascending aorta, the coronary arteries, or the heart for performing
cardiac procedures.
[0020] In one embodiment, the distal portion is shaped so that the
distal end of the shaft is spaced apart from any interior wall of
the aorta and the distal end is aligned with the center of the
aortic valve. By "shaped," it is meant that the distal portion of
the shaft is preset in a permanent, usually curved or bent shape in
an unstressed condition to facilitate positioning the distal
portion within at least a portion of the aortic arch. A shaft is
preferably for straightening the preshaped distal portion. Usually,
the straightening means comprises a straightening element slidably
disposed in the first inner lumen having a stiffness greater than
the stiffness of the preshaped distal portion. The straightening
element may comprise a relatively stiff portion of a flexible
guidewire extending through the first inner lumen, or a stylet
having an axial passage through it for receiving a movable
guidewire. Although it is preferred to provide a shaped-end and a
straightener, the shaped-end may be imparted to the distal portion
of the shaft with a shaping or deflecting element positioned over
or within the shaft.
[0021] The balloon may be made of an elastomeric material, such as
polyurethane, silicone or latex. In other embodiments, the
occlusion means may be an inflatable balloon made of a
nondistensible balloon material, such as polyethylene, polyethylene
terephthalate polyester, polyester copolymers, polyamide or
polyamide copolymers. The balloon is further configured to maximize
contact with the aortic wall to resist displacement and prevent
leakage around the balloon, preferably having a working surface for
contacting the aortic wall with a length in the range of about 1 to
about 7 cm, more preferably in the range of about 2 to 5 cm, when
the balloon is expanded to fully occlude the vessel.
[0022] When a balloon is used for the occluding means, the
endovascular device has an inflation lumen extending through the
shaft from the proximal end to the interior of the balloon, and
means connected to the proximal end of the inflation lumen for
delivering an inflation fluid to the interior of the balloon.
[0023] The shaft of the endovascular device may have a variety of
configurations. The first inner lumen and inflation lumen may be
coaxial, or a multilumen design may be employed. The shaft may
further include a third lumen extending from the proximal end to
the distal end of the shaft, allowing pressure distal to the
occluding means to be measured through the third lumen. The shaft
may also include means for maintaining the transverse dimensions of
the first inner lumen, which may comprise a wire coil or braid
embedded in at least the distal portion of the shaft to develop
radial rigidity without loss of longitudinal flexibility. The shaft
preferably has a soft tip at its distal end to prevent damage to
the heart valve if the catheter comes into contact with the
delicate valve leaflets.
[0024] The shaft preferably has a length of at least about 80 cm,
usually about 90-125 cm, to allow transluminal positioning of the
shaft from the femoral and iliac arteries to the ascending aorta.
Alternatively, the shaft may have a shorter length, e.g. 20-60 cm,
for introduction through the iliac artery, through the brachial
artery, through the carotid artery, or through a penetration in the
aorta itself.
[0025] The shaped distal portion of the device maintains the distal
end in a position spaced apart from the interior wall of the
ascending aorta so that the distal opening is unobstructed and
generally aligned with the center of the aortic valve. This
facilitates aspiration of blood, other fluids, or debris, infusion
of fluids, or introduction of instruments through the distal
opening in the endovascular device without interference with the
aortic wall or aortic valve tissue. The method may further include,
before the step of introducing the shaft into the blood vessel, the
steps of determining a size of the patient's aortic arch, and
selecting a shaft having a shaped distal portion corresponding to
the dimensions and geometry of the aortic arch.
[0026] Thus, using the aforementioned system and method, a
patient's heart can be arrested and the patient placed on
cardiopulmonary bypass without a thoracotomy, thereby reducing
mortality and morbidity, decreasing patient suffering, reducing
hospitalization and recovery time, and lowering medical costs
relative to open-chest procedures. The endovascular partitioning
permits blood flow through the ascending aorta to be completely
blocked between the coronary ostia and the brachiocephalic artery
in order to isolate the heart and coronary arteries from the
remainder of the arterial system. This has significant advantages
over the aortic cross-clamps used in current cardiac procedures,
not only obviating the need for a thoracotomy, but providing the
ability to stop blood flow through the aorta even when
calcification or other complications would make the use of an
external cross-clamp undesirable.
[0027] The system and method may further be useful to provide
cardiopulmonary bypass during endovascular interventional
procedures in which cardiac function may or may not be arrested.
Such procedures may include angioplasty, atherectomy, heart valve
repair and replacement, septal defect repair, treatment of
aneurysms, myocardial mapping and ablation, myocardial drilling,
and a variety of other procedures wherein endovascular
interventional devices are introduced through the bypass cannula of
the invention and advanced into the heart or great vessels. In this
way, the invention facilitates cardiopulmonary bypass during such
procedures without requiring additional arterial or venous
penetrations.
[0028] The aforementioned applications and patents describe an
endovascularly positionable occluding member which is used to
occlude the ascending aorta of the patient. Because of its
proximity to the left ventricle, the occluding member is subject to
pressure forces on both sides of the balloon. Pressure forces are
developed, for example, from the outflow of blood during systole.
Such forces threaten to displace the occluding means either
downstream, where it might occlude the ostium of the
brachiocephalic or other artery, or upstream where the occluding
member might damage the aortic valve or occlude the coronary ostia.
Advantageously, the shape of the distal end of the endovascular
device described above is configured to help maintain the position
of the occluding member in the ascending aorta against the force of
systolic outflow as the occluding member is expanded and retracted,
as well as during the period in which the occluding member fully
occludes the aorta but the heart remains beating.
[0029] Although the shaped distal end of the above-described
endovascular occluding member helps to prevent migration of the
occluding member, further features which reduce migration are
desirable given the potentially catastrophic consequences of
occluding member migration.
SUMMARY OF THE INVENTION
[0030] The present invention is directed to methods and devices for
anchoring an occluding member in a patient. A specific application
of the invention is described with respect to a method and system
for an endovascular approach for preparing a patient's heart for
cardiac procedures which does not require a grossly invasive
thoracotomy.
[0031] In an aspect of the present invention, the occluding member
is a balloon having surface features which enhance the frictional
engagement between the balloon and the aorta. The balloon
preferably includes an outer surface having a first portion with a
higher coefficient of friction than a second portion relative to
the occluded body part. The first portion preferably includes a
number of short ribs but may include any other surface feature
including radial ribs, spiral ribs, cross-hatching, knobs, a
frictional coating or any other surface feature so long as the
first portion has a higher coefficient of friction than the second
portion relative to the occluded body part. Although it is
preferred to enhance the frictional engagement of the first
portion, it is also within the scope of the invention to decrease
the frictional engagement between the second portion and the
occluded body part to achieve the same desired difference in
frictional engagement.
[0032] The second low-friction portion is preferably positioned at
a radially outward position relative to the first portion so that
when the balloon is advanced within the patient substantially only
the low friction portion contacts the body passageway. The balloon
preferably includes a number of low friction portions which are
positioned at radially outward portions of at least three, and
preferably at least four, arms. The high friction portion is
positioned between adjacent low friction portions and, further, the
high friction everts when the balloon moves from the collapsed
shape to the expanded shape. The term "collapsed" as used herein
refers to the overall configuration of the expandable member when
the expandable member is advanced within the patient to the desired
occluding position. An advantage of the present invention is that
the first, high-friction portion does not contact the body
passageway when the balloon is advanced within the patient thereby
reducing trauma and, furthermore, reducing the risk of releasing
plaque into the bloodstream.
[0033] The first portion is preferably integrally formed with the
second portion and is provided with a number of ribs and/or a
selective coating. A method of providing a selective coating and
other methods of providing a frictional surface are described in
PCT Application Number PCT/US94/09489 which is incorporated herein
by reference. Another method of providing high and low friction
portions would be to mask the low friction portion and sandblast
the high friction portion. Alternatively, a mandrel which is used
to make the balloon may have the high friction portion
sandblasted.
[0034] The present invention provides distinct advantages over PCT
Application Number PCT/US94/09489 since the radially-extending arms
help prevent the high friction portions from contacting the blood
vessel. A problem which might occur with the balloon of
PCT/US94/09489 is that the balloon might unravel when the balloon
is inserted into the patient thereby exposing the high friction
portions. Conversely, if the balloon is wrapped too tight, the
balloon may not open correctly when the balloon is inflated. The
present invention provides high friction portions which are exposed
but prevented from contacting the body passageway by the radially
outward portion of the arms.
[0035] In another aspect of the invention, pressure sensors are
provided on both sides of the balloon for measuring pressures
exerted on the balloon. In this manner, it can be determined when a
pressure differential exists across the expandable member which
might move the balloon upstream or downstream. The pressure sensors
are preferably coupled to an alarm which indicates when the
pressure differential exceeds a predetermined threshold pressure.
In a preferred embodiment, the pressure of cardioplegic fluid in
the ascending aorta is adjusted to reduce the pressure differential
to a value below the threshold pressure. The descriptive terms
downstream and upstream refer to the direction of blood flow and
the direction opposite normal blood flow, respectively. In the
arterial system, downstream refers to the direction away from the
heart and upstream refers to the direction toward to the heart. The
terms proximal and distal, when used herein in relation to
instruments used in the procedure, refer to directions closer to
and farther away from the operator performing the procedure,
respectively.
[0036] In another aspect of the invention, the pressure of the
balloon is monitored to optimize the inflation pressure. When
inflating the balloon, it is desirable to provide a high pressure
so that the balloon holding force is maximized to prevent
migration. On the other hand, it is desirable to minimize balloon
pressure so that aortic distention is minimized. In order to
provide a balloon pressure which balances these two concerns the
balloon pressure is monitored until a spike in the pressure vs.
fluid volume is detected. The pressure spike generally indicates
that the balloon has engaged the sidewall of the passageway. After
the pressure spike is detected, a predetermined amount of fluid is
added or the pressure of the balloon is increased a predetermined
amount so that the balloon pressure is optimized to enhance the
holding force on the balloon while preventing excessive aortic
distention.
[0037] In yet another aspect of the invention, the shaft of the
catheter is displaced and anchored so that a portion of the shaft
engages the aortic lumen for resisting balloon migration. The shaft
is preferably slidably coupled to a delivery cannula for movement
in both inward and outward directions. The shaft preferably
includes a first portion configured to contact the radially inner
wall of the aortic lumen when the shaft is slidably displaced in
the outward direction. The first portion anchors the shaft which,
in turn, anchors the occluding member. When the shaft is displaced
in the inward direction, a second portion engages the radially
outer wall of the aortic lumen. A preferred shape for the shaft
includes two bends and three substantially straight portions. The
first predetermined portion, which engages the radially inward wall
of the aorta, is preferably positioned between the first and second
bends.
[0038] In yet another aspect of the invention, an external clamp is
clamped near the occluded region to prevent migration of the
occluding member. The clamp may be positioned on one or both sides
of the occluding member. Alternatively, the clamp may be positioned
around the occluding member to prevent migration in both
directions.
[0039] A still further aspect of the invention provides an anchor
which extends into the brachiocephalic artery for preventing
upstream migration of an occluding member positioned in the
ascending aorta between the coronary ostia and the brachiocephalic
artery. The anchor is preferably a perfusion catheter configured to
deliver oxygenated blood to the brachiocephalic artery. The anchor
is preferably separate catheter but may also be integrally formed
with the occluding member catheter.
[0040] These and other advantages of the invention will become
apparent from the following detailed description of the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 schematically illustrates a cardiac access system
employing the endoaortic partitioning catheter of the present
invention.
[0042] FIG. 2 is a schematic partly cut-away representation of a
patient's heart with the endoaortic partitioning catheter of the
present invention placed within the ascending aorta.
[0043] FIG. 3 is a transverse cross-sectional view of the occluding
catheter shown in FIG. 2 taken along the lines 3-3.
[0044] FIG. 4. is an enlarged view, partially in section, of the
retrograde cardioplegia delivery catheter and the pulmonary venting
catheter shown in FIG. 1.
[0045] FIG. 5A is a longitudinal cross section of a first
embodiment of the endoaortic partitioning catheter of the present
invention. FIG. 5B is a lateral cross section of the catheter of
FIG. 5A taken along the lines 5B-5B. FIG. 5C is a lateral cross
section of the catheter of FIG. 5A taken along the lines 5C-5C.
FIG. 5D is a detail drawing showing the construction of section
5D-5D of the catheter of FIG. 5A.
[0046] FIG. 6A is a lateral side view of a second embodiment of the
endoaortic partitioning catheter. FIG. 6B is a lateral cross
section of the catheter of FIG. 6A taken along the lines 6B-6B.
FIG. 6C is a lateral cross section of the catheter of FIG. 6A taken
along the lines 6C-6C.
[0047] FIG. 7A is a longitudinal cross section of a third
embodiment of the endoaortic partitioning catheter having
piezoelectric pressure transducers. FIG. 7B is a lateral cross
section of the catheter of FIG. 7A taken along the lines 7B-7B.
FIG. 7C is a lateral cross section of the catheter of FIG. 7A taken
along the lines 7C-7C.
[0048] FIG. 8A is a longitudinal cross section of a fourth
embodiment of the endoaortic partitioning catheter having a
variable length occlusion balloon with the occlusion balloon
deflated. FIG. 8B is a longitudinal cross section of the catheter
of FIG. 8A with the occlusion balloon inflated in an elongated
position. FIG. 8C is a longitudinal cross section of the catheter
of FIG. 8A with the occlusion balloon inflated in a shortened
position. FIG. 8D shows the proximal end of an alternate embodiment
of the catheter of FIG. 8A.
[0049] FIG. 9A is a side view, partially in section, of a fifth
embodiment of the endoaortic partitioning catheter having a twisted
low-profile occlusion balloon. FIG. 9B is a longitudinal cross
section of the catheter of FIG. 9A with the occlusion balloon
inflated.
[0050] FIG. 10A is a front view of a sixth embodiment of the
endoaortic partitioning catheter having a precurved distal end.
FIG. 10B is a side view of the catheter of FIG. 10A. FIG. 10C is a
lateral cross section of the catheter of FIG. 10A taken along the
lines 10C-10C.
[0051] FIG. 11 is a schematic partly cut-away representation of a
patient's aortic arch with the endoaortic partitioning catheter of
FIG. 10A positioned in the ascending aorta.
[0052] FIG. 12A is a front view of a seventh embodiment of the
endoaortic partitioning catheter having a precurved distal end.
FIG. 12B is a side view of the catheter of FIG. 12A. FIG. 12C is a
lateral cross section of the catheter of FIG. 12A taken along the
lines 12C-12C.
[0053] FIG. 13 is a schematic partly cut-away representation of a
patient's aortic arch with the endoaortic partitioning catheter of
FIG. 12A positioned in the ascending aorta.
[0054] FIG. 14 is a front view of an eighth embodiment of the
endoaortic partitioning catheter having an eccentric aortic
occlusion balloon.
[0055] FIG. 15 is a schematic partly cut-away representation of a
patient's aortic arch with an endoaortic partitioning catheter
having a concentric occlusion balloon positioned in the ascending
aorta.
[0056] FIG. 16 is a schematic partly cut-away representation of a
patient's aortic arch with an endoaortic partitioning catheter
having an eccentric occlusion balloon positioned in the ascending
aorta.
[0057] FIG. 17 is a front view of an ninth embodiment of the
endoaortic partitioning catheter having an eccentric aortic
occlusion balloon.
[0058] FIG. 18A is a front view of a tenth embodiment of the
endoaortic partitioning catheter having an eccentric aortic
occlusion balloon. FIG. 18B is an end view of the catheter of FIG.
18A.
[0059] FIG. 19A is a front view of an eleventh embodiment of the
endoaortic partitioning catheter having a nondistensible aortic
occlusion balloon. FIG. 19B is an end view of the catheter of FIG.
19A. FIG. 19C is a side view of the catheter of FIG. 19A with the
occlusion balloon wrapped around the catheter shaft. FIG. 19D is an
end view of the catheter of FIG. 19C.
[0060] FIG. 20A is a front view of a twelfth embodiment of the
endoaortic partitioning catheter having a nondistensible aortic
occlusion balloon. FIG. 20B is an end view of the catheter of FIG.
20A. FIG. 20C is a side view of the catheter of FIG. 20A with the
occlusion balloon wrapped around the catheter shaft. FIG. 20D is an
end view of the catheter of FIG. 20C.
[0061] FIG. 21 is a schematic partly cut-away representation of a
patient's aortic arch with an endoaortic partitioning catheter
having a shaped occlusion balloon positioned in the ascending
aorta.
[0062] FIG. 22 is a schematic partly cut-away representation of a
patient's aortic arch with an endoaortic partitioning catheter
having a shaped occlusion balloon positioned in the ascending
aorta.
[0063] FIG. 23A is a schematic partly cut-away representation of a
patient's aortic arch with an endoaortic partitioning catheter
having a shaped occlusion balloon positioned in the ascending
aorta. FIG. 23B is a transverse cross section of the shaped
occlusion balloon of FIG. 23A.
[0064] FIG. 24 is a schematic partly cut-away representation of a
patient's aortic arch with an endoaortic partitioning catheter
having a shaped occlusion balloon positioned at the apex of the
aortic arch.
[0065] FIG. 25A illustrates an endoaortic partitioning catheter
with a curved tip for de-airing the heart and ascending aorta. FIG.
25B illustrates an alternate embodiment of an endoaortic
partitioning catheter for de-airing the heart and ascending
aorta.
[0066] FIG. 26 illustrates an endoaortic partitioning catheter
having a dumbbell-shaped occlusion balloon for centering the
catheter tip within the ascending aorta.
[0067] FIG. 27 illustrates an endoaortic partitioning catheter
having a steerable distal tip for centering the catheter tip within
the ascending aorta.
[0068] FIG. 28 illustrates an endoaortic partitioning
catheter-including a fiberoptic bundle for transillumination of the
aortic wall and/or for facilitating non-fluoroscopic placement of
the catheter.
[0069] FIG. 29 illustrates an endoaortic partitioning catheter
having an inflatable bumper balloon for protecting the aortic wall
from the catheter tip and for facilitating non-fluoroscopic
placement of the catheter.
[0070] FIG. 30A is a rear three-quarter view of a frictional
locking suture ring for use with the endoaortic partitioning
catheter. FIG. 30B is a front three-quarter view of the frictional
locking suture ring of FIG. 30A.
[0071] FIG. 31 is a front view of a dual function arterial cannula
and introducer sheath for use with the endoaortic partitioning
catheter.
[0072] FIG. 32 is a cross sectional view of the hemostasis fitting
of the dual function arterial cannula and introducer sheath of FIG.
31.
[0073] FIG. 33 illustrates the cannula of FIG. 31 with an
endoaortic partitioning catheter introduced into the catheter
insertion chamber.
[0074] FIG. 34 illustrates the cannula of FIGS. 31 and 32 with the
endoaortic partitioning catheter introduced into the patient's
femoral artery.
[0075] FIGS. 35A-35C illustrate an endoaortic partitioning catheter
having a steerable distal tip with a multichamber balloon for
centering the catheter tip within the ascending aorta.
[0076] FIG. 36 illustrates a multifunction embodiment of the
endoaortic partitioning catheter combined with a dual function
arterial cannula and introducer sheath and a frictional locking
suture ring.
[0077] FIG. 37 shows a balloon having a first, high friction
portion and a second, low friction portion.
[0078] FIG. 38 is an end view of the balloon of FIG. 37.
[0079] FIG. 39 is an end view of the balloon of FIG. 37 in an
expanded state.
[0080] FIG. 40 is an isometric view of a second preferred balloon
having a first, low friction portion and a second, high friction
portion.
[0081] FIG. 41 is an end view of the balloon of FIG. 40.
[0082] FIG. 42 is a side view of an aorta with clamps positioned on
both sides of the occluding member to prevent migration of the
occluding member;
[0083] FIG. 43 is a plan view of the clamp of FIG. 42.
[0084] FIG. 44A is a side view of an aorta with the clamp of FIG.
42 positioned around the aorta and a balloon trapped by the clamp
in the aorta.
[0085] FIG. 44B is a plan view of an intermediate wall positioned
in an indentation of the balloon of FIG. 44A.
[0086] FIG. 45 is a partial cross-sectional view of the delivery
cannula of FIGS. 33 and 34 with a shaft displacing mechanism.
[0087] FIG. 46 is a side view of an aorta with the shaft displaced
in an outward direction so that the shaft engages a radially inner
wall of the aorta.
[0088] FIG. 47 is a side view of an aorta with a shaft having a
two-bend configuration displaced in an inward direction so that the
shaft of FIG. 46 engages a radially outer wall of the aorta.
[0089] FIG. 48 is a side view of an aorta with a shaft having a
hook-shaped portion displaced in an outward direction so that the
shaft engages a radially inner wall of the aorta.
[0090] FIG. 49 is a side view of an aorta with the shaft of FIG. 48
displaced in an inward direction so that the shaft engages a
radially outer wall of the aorta.
DETAILED DESCRIPTION OF THE INVENTION
[0091] The invention provides a cardiac access system including an
endovascular device for partitioning the ascending aorta, as well
as a system for selectively arresting the heart, which are useful
in performing a variety of cardiovascular, pulmonary,
neurosurgical, and other procedures. The procedures with which the
invention will find use include repair or replacement of aortic,
mitral, and other heart valves, repair of septal defects, pulmonary
thrombectomy, electrophysiological mapping and ablation, coronary
artery bypass grafting, angioplasty, atherectomy, treatment of
aneurysms, myocardial drilling and revascularization, as well as
neurovascular and neurosurgical procedures. The invention is
especially useful in conjunction with minimally-invasive cardiac
procedures, in that it allows the heart to be arrested and the
patient to be placed on cardiopulmonary bypass using only
endovascular devices, obviating the need for a thoracotomy or other
large incision. Moreover, even in conventional open-chest
procedures, the endovascular aortic partitioning device of the
invention will frequently find use where an external cross-clamp
would raise substantial risks of embolus release due to
calcification or other aortic conditions.
[0092] Reference is made to FIG. 1 which schematically illustrates
the overall cardiac accessing system of the invention and the
individual components thereof. The accessing system includes an
elongated aortic occlusion or endoaortic partitioning catheter 10
which has an expandable member 11 on a distal portion of the
catheter which, when inflated as shown, occludes the ascending
aorta 12 to separate or partition the left ventricle 13 and
upstream portion of the ascending aorta from the rest of the
patient's arterial system and securely positions the distal end of
the catheter within the ascending aorta. A cardiopulmonary bypass
system 18 removes venous blood from the femoral vein 16 through the
blood withdrawal catheter 17 as shown, removes CO.sub.2 from the
blood, oxygenates the blood, and then returns the oxygenated blood
to the patient's femoral artery 15 through the return catheter 19
at sufficient pressure so as to flow throughout the patient's
arterial system except for the portion blocked by the expanded
occluding member 11 on the aortic occluding catheter 10. The aortic
occluding catheter 10 has an infusion lumen 40 for antegrade
delivery of a fluid containing cardioplegic agents directly into
the aortic root 12 and subsequently into the coronary arteries 52,
53 (shown in FIG. 2) to paralyze the patient's myocardium.
Optionally, a retrograde cardioplegia balloon catheter 20 may be
disposed within the patient's venous system with the distal end of
the catheter extending into the coronary sinus 21 (shown in FIG. 4)
to deliver a fluid containing cardioplegic agents to the myocardium
in a retrograde manner through the patient's coronary venous system
to paralyze the entire myocardium.
[0093] The elongated occluding catheter 10 extends through the
descending aorta to the left femoral artery 23 and out of the
patient through a cut down 24. The proximal extremity 25 of the
catheter 10 which extends out of the patient is provided with a
multi-arm adapter 26 with one arm 27 adapted to receive an
inflation device 28. The adapter 26 is also provided with a second
arm 30 with main access port 31 through which passes instruments, a
valve prosthesis, an angioscope, or to direct blood, irrigation
fluid, cardioplegic agents and the like to or from the system. A
third arm 32 is provided for monitoring aortic root infusion
pressure at the distal end of the catheter and/or for directing
blood, irrigation fluid, and the like to or from the system. In the
system configuration of FIG. 1, the third arm 32 of the multi-arm
adapter 26 is connected to a cardioplumonary bypass line 33 to vent
the patient's heart, particularly the left ventricle, and to
recover the blood removed and return it to the patient via the
cardiopulmonary bypass system. A suitable valve 34 is provided to
open and close the bypass line 33 and direct the fluid passing
through the bypass line to a discharge line 35 or a line 36 to a
blood filter and recovery unit 37. A return line may be provided to
return any filtered blood to the cardiopulmonary bypass system 18
or other blood conservation system.
[0094] The details of the aortic occlusion catheter 10 and the
disposition of the distal extremity thereof within the aorta are
best illustrated in FIGS. 2 and 3. As indicated, the catheter 10
includes an elongated catheter shaft 39 which has a first inner
lumen 40 for infusion of a cardioplegic agent in fluid
communication with the main access port 31 in the second arm of the
adapter 26. Additionally, the infusion lumen 40 may be adapted to
facilitate the passage of instruments, a valve prosthesis, an
angioscope, irrigation fluid, and the like therethrough and out the
distal port 41 in the distal end thereof. A supporting coil 42 may
be provided in the distal portion of the first inner lumen 40 to
prevent the catheter shaft 39 from kinking when it straightened for
initial introduction into the arterial system or when it is
advanced through the aortic arch. The shaft 39 is also provided
with a second inner lumen 43 which is in fluid communication with
the interior of the occluding balloon 11.
[0095] In one embodiment of the system, a retrograde cardioplegia
balloon catheter 20, which is shown in more detail in FIG. 4, is
introduced into the patient's venous system through the right
internal jugular vein 44 and is advanced through the right atrium
45 and into the coronary sinus 21 through the coronary sinus
discharge opening 46 in the right atrium. The retrograde catheter
20 is provided with a balloon 47 on a distal portion of the
catheter 20 which is adapted to occlude the coronary sinus 21 when
inflated. A liquid containing a cardioplegic agent, e.g. an aqueous
KCl solution, is introduced into the proximal end 48 of the
catheter 20, which extends outside of the patient, under sufficient
pressure so that the fluid containing the cardioplegic agent can be
forced to pass through the coronary sinus 21, through the capillary
beds (not shown) in the patient's myocardium, through the coronary
arteries 50 and 51 and ostia 52 and 53 associated with the
respective coronary arteries into the blocked off portion of the
ascending aorta 12 as shown.
[0096] A pulmonary venting catheter 54 is also shown in FIG. 4
disposed within the right internal jugular vein 44 and extending
through the right atrium 45 and right ventricle 55 into the
pulmonary trunk 56. Alternatively, the pulmonary venting catheter
54 may be introduced through the left jugular. The catheter 54
passes through tricuspid valve 57 and pulmonary valve 58. An
inflatable occluding balloon 60 may be provided as shown on a
distal portion of the pulmonary venting catheter 54 which is
inflated to occlude the pulmonary trunk 56 as shown. The pulmonary
venting catheter 54 has a first inner lumen 61 which extends from
the distal end of the catheter to the proximal end of the catheter
which vents fluid from the pulmonary trunk 56 to outside the
patient's body either for discharge or for passage to the blood
recovery unit and thereby decompresses the left atrium 14 through
the pulmonary capillary beds (not shown). The catheter 54 has a
second inner lumen 62 which is adapted to direct inflation fluid to
the interior of the inflatable balloon 60.
[0097] To set up the cardiac access system, the patient is
initially placed under light general anesthesia. The withdrawal
catheter 17 and the return catheter 19 of the cardiopulmonary
bypass system 18 are percutaneously introduced into the right
femoral vein 16 and the right femoral artery 15, respectively. An
incision 24 is also made in the left groin to expose the left
femoral artery 23 and the aortic occluding catheter 10 is inserted
into the left femoral artery through an incision therein and
advanced upstream until the balloon 11 on the distal end of the
occluding catheter 10 is properly positioned in the ascending aorta
12. Note that bypass could similarly be established in the left
groin and the aortic occlusion catheter put into the right femoral
artery. The retrograde perfusion catheter 20 is percutaneously
inserted by a suitable means such as the Seldinger technique into
the right internal jugular vein 44 or the subclavian vein and
advanced into the right atrium 45 and guided through the discharge
opening 46 into the coronary sinus.
[0098] The pulmonary venting catheter 54 is advanced through the
right or left internal jugular vein 44 or the subclavian vein
(whichever is available after introduction of retrograde perfusion
catheter 20) into the right atrium 45, right ventricle 55, and into
the pulmonary trunk 56. The occluding balloon 60 may be inflated if
necessary by inflation with fluid passing through the lumen 62 to
block the pulmonary trunk 56 and vent blood therein through the
lumen 61 where it is discharged through the proximal end of the
catheter which extends outside of the patient. Alternatively, the
occluding balloon 60 may be partially inflated with air or CO.sub.2
during introduction for flow-assisted placement. The venting of the
pulmonary trunk 56 results in the decompressing of the left atrium
14 and, in turn, the left ventricle. In the alternative, the
venting catheter 54 may be provided with means on the exterior
thereof, such as expanded coils as described in U.S. Pat. No.
4,889,137 (Kolobow), which hold open the tricuspid and pulmonary
valves and perform the same function of decompressing the left
atrium. See also the article written by F. Rossi et. al. in the
Journal of Thoracic Cardiovascular Surgery, 1900; 100: 914-921,
entitled "Long-Term Cardiopulmonary Bypass By Peripheral
Cannulation In A Model Of Total Heart Failure", which is
incorporated herein in its entirety by reference.
[0099] The operation of the cardiopulmonary bypass unit 18 is
initiated to withdraw blood from the femoral vein 16 through
catheter 17, remove CO.sub.2 from and add oxygen to the withdrawn
blood and then pump the oxygenated blood through the return
catheter 19 to the right femoral artery 15. The balloon 11 may then
be inflated to occlude the ascending aorta 12, causing the blood
pumped out of the left ventricle (until the heart stops beating due
to the cardioplegic fluid as discussed hereinafter) to flow through
the discharge port 41 into the first inner lumen 40 of the
occluding catheter. The blood flows through the inner lumen 40 and
out the third arm 32 of the adapter 26 into the bypass line 33 and
then into the blood filter and blood recovery unit 37 through the
valve 34 and line 36. For blood and irrigation fluids containing
debris and the like, the position of the valve 34 may be changed to
direct the fluid through the discharge line 35.
[0100] In a first embodiment of the method, a liquid containing a
cardioplegic agent such as KCl is directed through the infusion
lumen 40 of the catheter 10 into the aortic root 12 and
subsequently into the coronary arteries 52, 53 to paralyze the
patient's myocardium. Alternatively, if a retroperfusion catheter
20 is provided for delivery of the cardioplegic agent, the balloon
47 on the distal extremity of the catheter 20 is inflated to
occlude the coronary sinus 21 to prevent fluid loss through the
discharge opening 46 into the right atrium 45. A liquid containing
a cardioplegic agent such as KCl is directed through the catheter
20 into the coronary sinus 21 and the pressure of the cardioplegic
fluid within the coronary sinus 21 is maintained sufficiently high,
(e.g. 40 mm Hg) so that the cardioplegic fluid will pass through
the coronary veins, crossing the capillary beds to the coronary
arteries 50 and 51 and out the ostia 52 and 53. The cardioplegic
fluid pressure within the coronary sinus 21 should be maintained
below 75 mm Hg to avoid pressure damage to the coronary sinus 21.
Once the cardioplegic fluid passes through the capillary beds in
the myocardium, the heart very quickly stops beating. At that point
the myocardium is paralyzed and has very little demand for oxygen
and can be maintained in this state for long periods of time with
minimal damage.
[0101] With the cardiopulmonary bypass system in operation, the
heart completely paralyzed and not pumping, the left atrium and
ventricle decompressed and the ascending aorta blocked by the
inflated balloon 11 on the occluding catheter 10, the heart is
appropriately prepared for a cardiac procedure.
[0102] Inflation of the inflatable member 11 on the distal end of
the delivery catheter 10 fixes the distal end of the occluding
catheter 10 within the ascending aorta 12 and isolates the left
ventricle 13 and the upstream portion of the ascending aorta from
the rest of the arterial system downstream from the inflatable
member. The passage of any debris or emboli, solid or gaseous,
generated during a cardiovascular procedure to regions downstream
from the site would be precluded by the inflated balloon 11. Fluid
containing debris or emboli can be removed from the region between
the aortic valve and the occluding balloon 11 through the inner
lumen 40 of catheter 10. A clear, compatible fluid, e.g. an aqueous
based fluid such as saline delivered through the inner lumen 40 or
the cardioplegic fluid discharging from the coronary ostia 52 and
53, may be maintained in the region wherein the cardiovascular
procedure is to be performed to facilitate use of an angioscope or
other imaging means that allows for direct observation of the
cardiac procedure. Preferably, the fluid pressure in the left
ventricle 13 is maintained sufficiently higher than that in the
left atrium to prevent blood from the left atrium from seeping into
the left ventricle and interfering with the observation of the
procedure.
[0103] FIG. 5A shows a longitudinal cross section of a first
preferred embodiment of the endoaortic partitioning catheter 100 of
the present invention. The endoaortic partitioning catheter 100 of
FIG. 5A is made with a coaxial construction, which indicates that
the catheter 100 is constructed of a first, inner tube 102 within a
second, outer tube 104. The inner tube 102 and the outer tube 104
of the catheter 100 combine to form an elongated shaft 106 that
runs from a proximal hub 108 to the distal end of the catheter 100
having an aortic occlusion balloon 110 mounted thereon. The length
of the shaft 106 is such that the catheter 100 can be introduced
into the patient's aorta by way of an arterial cutdown or the
Seldinger technique into a peripheral artery, such as the femoral
or brachial artery, and advanced into the ascending aorta. For
introduction by way of a femoral artery or iliac artery the length
of the shaft 106 is preferably 80 to 125 cm. For introduction by
way of a brachial artery, the carotid artery or through a
penetration directly into the aorta, the length of the shaft 106 is
preferably 20 to 80 cm.
[0104] In the embodiment of FIG. 5A, the inner tube 102 of the
catheter 100 is a two lumen tube, having a crescent-shaped
cardioplegia infusion lumen 112 which wraps around a circular
distal pressure lumen 114, as shown in cross section in FIGS. 5B
and 5C. The cardioplegia infusion lumen 112 and the distal pressure
lumen 114 are open at the distal end of the catheter 100. The
cardioplegia infusion lumen 112 preferably has a cross sectional
area sufficient for delivering a mixture of warm or cooled,
oxygenated blood and cardioplegia solution at a rate of from about
200 ml/min to 400 ml/min with an infusion pressure not to exceed
300 mm Hg. In one presently preferred embodiment, the cross
sectional area of the cardioplegia infusion lumen 112 is
approximately 5.74 mm.sup.2 (0.00889 in.sup.2) for a catheter with
a length of about 120-130 cm. The cross sectional area of the
cardioplegia infusion lumen 112 necessary to deliver the desired
flow rate will vary somewhat depending on the length of the
catheter shaft 106 and the ratio of blood to cardioplegic solution
in the mixture. The distal pressure lumen 114 preferably has a
cross sectional area sufficient to transmit the pressure within the
aortic root along the length of the catheter shaft 106 without
excessive damping of the pressure wave. In a preferred embodiment
having a shaft length of about 120-130 cm, a distal pressure lumen
114 having an internal diameter of 0.61 mm, and therefore a cross
sectional area of 0.29 mm.sup.2 (0.00045 in.sup.2), provides the
desired pressure signal transmission.
[0105] The outer tube 104 of the catheter 100 fits coaxially around
the inner tube 102 with an annular space between the two tubes
providing a balloon inflation lumen 116, as shown in cross section
in FIG. 3C. The external diameter of the catheter 100 can be made
within the range of 8-23 French (Charrire scale), preferably in the
range of 8-12 French. In one preferred embodiment of the catheter
100, the outer tube 104 has an external diameter of 3.4-3.5 mm or
approximately 10.5 French (Charri{fraction (e)}re scale). In a
second preferred embodiment of the catheter 100, the outer tube 104
has an external diameter of 3.2-3.3 mm or approximately 10 French
(Charrire scale). An aortic occlusion balloon 110 is mounted on the
distal end of the catheter 100. The aortic occlusion balloon 110
has a proximal balloon neck 118 which is sealingly attached to the
outer tube 104 and a distal balloon neck 120 which is sealingly
attached to the inner tube 102 of the catheter 100 so that the
balloon inflation lumen 116 communicates with the interior of the
balloon 110. Preferably, the balloon inflation lumen 116 has a
cross sectional area of approximately 0.5-1.0 mm.sup.2
(0.00077-0.00155 in.sup.2) to allow rapid inflation and deflation
of the aortic occlusion balloon 110. In a particular presently
preferred embodiment with the described configuration, the balloon
inflation lumen 116 has a cross sectional area of approximately
0.626 mm.sup.2 (0.00097 in.sup.2) which allows the occlusion
balloon 110 be inflated to a recommended maximum volume of 40 cc
with saline solution or saline solution mixed with a radiopaque
contrast agent at an inflation pressure of 35 psi in 40 seconds or
less, preferably in 20 seconds or less. Whether inflating by hand
or using a mechanical inflation device, the inflation of the
balloon is preferably volume-limited so that, although the
transient, peak inflation pressure reaches approximately 35 psi,
the inflation pressure decreases to about 10-12 psi to maintain
balloon inflation when the balloon reaches its desired inflation
volume. The balloon inflation lumen 116 also allows the occlusion
balloon 110 be deflated in 60 seconds or less, preferably in 40
seconds or less. The occlusion balloon 110 can be inflated and
deflated by hand using an ordinary syringe or it can be inflated
and deflated using an inflation device which provides a mechanical
advantage or that is powered by compressed air or an electric
motor.
[0106] FIG. 5D is a detail drawing showing the construction of
section 5D-5D of the catheter 100 of FIG. 5A. The proximal balloon
neck 118 is bonded to the distal end of the outer tube 104 in a lap
joint. The bond between the proximal balloon neck 118 and the outer
tube 104 and the bond between the distal balloon neck 120 and the
inner tube 102 can be formed by adhesive bonding, by solvent
bonding or by heat bonding depending on the materials chosen for
each component. Alternatively, the outer tube 104 can be formed
from a single continuous extrusion with the material of the aortic
occlusion balloon 110.
[0107] The proximal hub 108 of the catheter 100 has a luer fitting
balloon inflation port 122 that is sealingly connected to the
balloon inflation lumen 116, a luer fitting pressure monitoring
port 124 that is sealingly connected to the distal pressure lumen
114, and an infusion port 126 that is sealingly connected to the
cardioplegia infusion lumen 112. The proximal hub 108 may be joined
to the proximal ends of the inner tube 102 and the outer tube 104
by adhesive bonding, by insert molding or by other known
processes.
[0108] In the embodiment of FIG. 5A, the aortic occlusion balloon
110 is shown as having a generally spherical geometry in the
unexpanded state 110, as well as a generally spherical geometry in
the expanded or inflated state 110'. Other possible geometries for
the balloon in the unexpanded state 110 include cylindrical, oval
or football-shaped, eccentric or other shaped balloons. Some of
these variations are further described below. In this preferred
embodiment the balloon 110 is made of an elastomeric material that
expands elastically from the uninflated to the inflated state.
Preferred materials for the balloon 110 include latex, silicone,
and polyurethane, chosen for their elasticity, strength and
biocompatibility for short term contact with the blood and body
tissues.
[0109] FIG. 6A shows a lateral side view of a second preferred
embodiment of the endoaortic partitioning catheter 200. In this
embodiment the inner tube 202 has been made with a D-shaped
cardioplegia infusion lumen 212 and a D-shaped distal pressure
lumen 214. The choice of D-shaped lumens in the inner tube 202,
makes it possible to maximize the diametrical clearance within the
cardioplegia infusion lumen 212 for a given cross sectional area,
as compared to the crescent-shaped cardioplegia infusion lumen 112
of FIG. 5C. This variation of the catheter 200 may be preferable
when catheters or other instruments are to be introduced to the
heart and its associated blood vessels through the cardioplegia
infusion lumen 212.
[0110] As shown in FIG. 6A, the occlusion balloon 210 of this
embodiment has an ellipsoidal or football-shaped deflated profile
which is imparted by the balloon molding process. The wall
thickness of the molded balloon 210 in its deflated state is
typically about 0.090-0.130 mm. Typically, the deflated balloon 210
has a diameter of approximately 12 mm before it is folded, although
deflated balloon diameters of 3 to 20 mm are possible. The inflated
balloon 210' assumes a roughly spherical shape with a maximum
diameter of approximately 40 mm when inflated. The football shape
of the molded balloon has been shown to be advantageous in that the
deflated balloon 210 has a deflated profile which is less bulky and
smoother than for other balloon geometries tested. This allows the
deflated balloon 210 to be folded and more easily inserted through
a percutaneous puncture into the femoral artery or through an
introducer sheath or a dual function arterial cannula and
introducer sheath. In this embodiment as well, the balloon 210 is
preferably made of an elastomeric material such as latex, silicone,
or polyurethane. In one particular embodiment, the football-shaped
balloon has an internal geometry determined by a positive dip
molding mandrel with a radius of curvature in the central portion
of the balloon of approximately 1.0 inch with a maximum diameter in
the center of the balloon of about 0.5 inch. The curvature of the
central portion of the balloon has a smoothly radiused transition,
for example with a radius of about 0.25 inch, to the proximal and
distal balloon sleeves, which are sized to fit snugly onto the
exterior of the chosen diameter catheter shaft.
[0111] FIG. 7A shows a longitudinal cross section of a third
preferred embodiment of the endoaortic partitioning catheter 300.
The catheter 300 of this embodiment has a coaxial construction
having a single lumen inner tube 302 surrounded by a single lumen
outer tube 304. The single lumen inner tube 302 has a circular
cardioplegia infusion lumen 312 that is connected on its proximal
end to the infusion port 326 of the proximal hub 308 of the
catheter 300. The cardioplegia infusion lumen 312 is open at the
distal end of the catheter 300. The single lumen outer tube 304 of
the catheter 300 fits coaxially around the inner tube 302 with an
annular space between the two tubes providing a balloon inflation
lumen 316. The balloon inflation lumen 316 is connected on its
proximal end to the balloon inflation port 322 of the proximal hub
308.
[0112] In this embodiment, the aortic root pressure monitoring
function is fulfilled by a distal pressure transducer 330 mounted
at the distal tip 332 of the catheter 300. The distal pressure
transducer 330 electronically monitors the aortic root pressure and
transmits a signal along signal wires 334 and 336 to electrical
connections 338 and 340 within an electrical connector 324 on the
proximal hub 308 of the catheter 300. The electrical connector is
adapted to be connected to an electronic pressure monitor which
displays an analog or digital indication of the pressure at the
distal end 332 of the catheter 300. The distal pressure transducer
330 is preferably a piezoelectric pressure transducer which creates
a voltage signal indicative of the external fluid pressure exerted
on the transducer 330. Examples of piezoelectric materials suitable
for construction of the distal pressure transducer 330 include
piezoelectric polymers such as polyvinylidene bifluoride or
Kynar.TM. (Elf Atochem SA), or piezoelectric ceramics such as lead
barium titanate, zirconium barium titanate or other commercially
available piezoelectric materials. The geometry of the distal
pressure transducer 330 may be a ring encircling the distal tip 332
of the catheter 300, as shown in FIGS. 7A and 7B. Alternatively, a
small patch of the piezoelectric material may be mounted on one
side of the distal tip 332 of the catheter 300. The distal pressure
transducer 330 preferably has a pressure sensing range from about
-75 to 300 mm Hg or greater (-1.5 to 5.7 psi) so as to be able to
measure root pressure during cardioplegia infusion and during
venting of the aortic root.
[0113] Optionally, a balloon pressure monitoring transducer 350 may
also be mounted within the balloon 310 of the catheter 300 for
monitoring the inflation pressure of the balloon 310. The balloon
pressure monitoring transducer 350 electronically monitors the
balloon inflation pressure and transmits a signal along signal
wires 352 and 354 to electrical connections 356 and 358 within the
electrical connector 324 on the proximal hub 308 of the catheter
300. The balloon pressure monitoring transducer 350 is preferably a
piezoelectric pressure transducer which creates a voltage signal
indicative of the external fluid pressure exerted on the transducer
350, made for example from one the piezoelectric polymers or
piezoelectric ceramics designated above in connection with the
distal pressure transducer 330. The balloon pressure monitoring
transducer 350 preferably has a pressure sensing range from about
-760 to 300 mm Hg or greater (-15 to 35 psi) so as to be able to
measure balloon pressure during inflation and deflation of the
occlusion balloon 310. The balloon pressure monitoring transducer
350 can be used to monitor internal balloon pressure to make sure
that the occlusion balloon 310 has been inflated to proper pressure
to insure reliable occlusion of the ascending aorta. The balloon
pressure monitoring transducer 350 can also be used to determine
when the occlusion balloon 310 has contacted the interior wall of
the ascending aorta by monitoring for a spike in the inflation
pressure within the balloon or for an inflection point in the
pressure/volume curve while inflating. A safe inflation volume can
be determined for each individual patient by a protocol wherein the
occlusion balloon 310 is inflated until it contacts the interior
wall of the ascending aorta, then a set volume of inflation fluid
is added to create a reliable seal to occlude the aortic lumen.
Alternatively, the protocol for inflation could include determining
when the occlusion balloon 310 contacts the aortic wall and
incrementally increasing the pressure a set amount to form a
seal.
[0114] In a specific embodiment, the pressure transducer 350
monitors the pressure in the balloon 310 and transmits the pressure
information to a pressure monitor 353 via signal wires 352, 354 and
electrical connections 356, 358. The pressure monitor 353 is also
coupled to a source of inflation fluid 355 for determining an
amount of inflation fluid injected into the balloon 310. The
pressure monitor 353 is configured to determine the rate of
pressure increase relative to the fluid volume injected in the
balloon 351 from the fluid source 355. The pressure monitor 353
determines when a pressure spike in the pressure vs. fluid volume
is detected. The pressure spike generally indicates that the
balloon 310 has engaged the aortic lumen at which point the
pressure increases more rapidly with respect to the fluid volume.
The slope of the pressure spike which triggers the pressure monitor
353 depends upon a number of factors including the size, shape and
elasticity of the balloon 310. It is contemplated that the
magnitude of the pressure spike may be determined empirically by
testing balloons with various size passageways. After the pressure
spike is detected, the pressure monitor 353 sends a signal to the
source of inflation fluid 355 to either add a predetermined amount
of fluid or to add fluid until a predetermined increase in pressure
is sensed. The predetermined amount of fluid and/or predetermined
increase in pressure both add an additional amount of holding force
to prevent migration of the balloon while minimizing distention of
the aorta.
[0115] In yet another aspect of the invention, the catheter
includes a proximal pressure transducer 331 which monitors the
pressure on a proximal side of the balloon 351 and transmits a
signal to the pressure monitor 353 via wires 339, 341. The pressure
transducer 330 and proximal pressure transducer 331 are coupled to
the pressure monitor 353 which monitors the pressures and,
furthermore, determines a pressure differential between the
transducers 330, 331. The pressure monitor 353 preferably includes
an alarm 357, which may be a visual or audible alarm, which tells
the user that the pressure differential measured by the transducers
330, 331 exceeds a predetermined threshold.
[0116] When the pressure differential exceeds the predetermined
threshold, the pressure on one or both sides of the balloon 351 is
adjusted so that the pressure differential does not exceed the
predetermined threshold. When the catheter 300 is used in
conjunction with cardiopulmonary bypass as explained above, the
catheter 300 delivers cardioplegic fluid through the infusion port
from a source of cardioplegic fluid 359. The delivery of
cardioplegic fluid from the source of cardioplegic fluid 359 may be
adjusted so that the pressure differential does not exceed the
predetermined threshold. Alternatively, the pressure on the
proximal side of the balloon may be adjusted so that the pressure
differential is below the threshold differential pressure. The
above described embodiments having the pressure transducers 330,
350, 331 and pressure monitors 353 described in conjunction with
the embodiment of FIG. 7A may be used with any other occluding
member or balloon and are generally directed to techniques for
minimizing migration of occluding members. Furthermore, although
the use of pressure transducers 330, 350, 331 is preferred, any
other devices for measuring the balloon and fluid pressures may be
used without departing from the scope of the invention.
[0117] The signal wires 334, 336, 339, 341, 352, 354 from the
pressure transducers 330, 350, 331 extend through the annular
inflation lumen 316 between the inner tube 302 and the outer tube
304. The signal wires 334, 336, 352, 354, 339, 341 may be laid
loosely in the inflation lumen 316 with some slack, or they may be
spiraled around the inner tube 302 so that they do not adversely
affect the bending characteristics of the catheter 300.
Alternatively, the signal wires may be embedded in the wall of the
inner tube 302, either during the extrusion process or in a
post-extrusion operation. In order to have electrical impedance to
match the impedance of the transducers 330, 350 and/or the
electronic pressure monitor 353, the signal wires may be provided
as parallel pairs, twisted pairs or coaxial cables, as
required.
[0118] The use of a distal pressure transducer 330 for monitoring
aortic root pressure eliminates the need for a separate pressure
monitoring lumen in the catheter as provided in the embodiments of
FIGS. 5A and 6A. This allows a reduction in the catheter external
diameter without sacrificing catheter performance in terms of the
cardioplegia flow rate in the infusion lumen 312 and the speed of
balloon inflation and deflation through the balloon inflation lumen
316. A 10 French (3.3 mm external diameter) catheter constructed
according to this design provides a flow rate and balloon inflation
performance comparable to a 10.5 French (3.5 mm external diameter)
catheter constructed with a separate pressure monitoring lumen.
Reducing the external diameter of the catheter in this way has a
number of clinical advantages. The smaller diameter catheter will
be easier to introduce into a patient's femoral, brachial or other
artery by either the Seldinger technique or by an arterial cutdown
or by insertion through an introducer sheath. It will also be
possible to introduce the smaller diameter catheter into smaller
arteries, as encountered in smaller patients, particularly female
and pediatric patients. This will increase the clinical
applicability of the catheter and the method for its use to a
greater patient population. In all patients, the smaller diameter
catheter will cause less trauma to the artery it is introduced
through, thereby reducing the likelihood of complications, such as
bleeding or hematoma at the arterial access site. The smaller
diameter catheter will also be particularly advantageous when used
in conjunction with the dual function arterial cannula and
introducer sheath described below in relation to FIGS. 31-34
because the smaller diameter shaft will occupy less of the blood
flow lumen of the cannula, allowing higher blood flow rates at
lower pressures. With these improvements, the external diameter of
an endoaortic partitioning catheter for use with warm blood
cardioplegia can be reduced to 8 to 10 French (2.7-3.3 mm external
diameter) and for use with crystalloid cardioplegia can be reduced
to 7 to 9 French (2.3-3.0 mm external diameter). Although use of
the pressure transducers have been described in connection with the
inflatable balloon of FIG. 7A, the pressure transducers may be used
with any other occluding member without departing from the scope of
the invention.
[0119] Further improvements in reducing the effective diameter of
the catheter during introduction or removal of the catheter from
the peripheral arterial access site can be accomplished by making
the occlusion balloon self-collapsing around the catheter. Two
embodiments of coaxial-construction catheters with self-collapsing
occlusion balloons are shown in FIGS. 8A-8C and 9A-9B.
[0120] FIG. 8A shows a transverse cross section of a
coaxial-construction endoaortic partitioning catheter 400 in which
the inner tube 402 and the outer tube 404 are axially movable with
respect to one another. The inner tube 402 has a cardioplegia
infusion lumen 412 and a pressure monitoring lumen 414. The inner
tube 402 is connected to a first proximal hub 430 with luer fitting
connections 426 and 424 in communication with the cardioplegia
infusion lumen 412 and the pressure monitoring lumen 414,
respectively. The outer tube 404 fits coaxially around the inner
tube 402 with an annular space between the two tubes providing a
balloon inflation lumen 416. The outer tube 404 is connected to a
second proximal hub 432 with a luer fitting connection 422 for the
balloon inflation lumen 416. The inner tube 402 passes through the
second proximal hub 432 exiting through a sliding fluid seal 440
that allows axial movement of the inner tube 402 with respect to
the second proximal hub 432 and the outer tube 404.
[0121] In one preferred embodiment the sliding fluid seal 440 is a
type of compression fitting known in the industry as a Tuohy-Borst
adapter. The Tuohy-Borst adapter 440 has a compressible tubular or
ring-shaped elastomeric seal 442 that fits within a bore 446 on the
proximal end of the second proximal hub 432. A threaded compression
cap 444 fits onto the proximal end of the second proximal hub 432.
When the compression cap 444 is tightened, it compresses the
elastomeric seal 442 axially, which causes the lumen 448 of the
seal 442 to narrow and seal against the inner tube 402. The
Tuohy-Borst adapter 440 can also be used to lock the position of
the inner tube 402 with respect to the second proximal hub 432 and
the outer tube 404 by tightening the compression cap 444 until the
friction between the elastomeric seal 442 and inner tube 402
effectively locks them together to prevent axial movement between
the two.
[0122] In a second preferred embodiment, shown in FIG. 8D, a
sliding fluid seal 440 is combined with a locking mechanism 450 to
lock the inner tube 402 with respect to the outer tube 404 to
prevent axial movement between the two. The locking mechanism 450
may comprise a threaded shaft 452 in alignment with the inner tube
402 and a lock nut 454 threaded onto the shaft 452. By turning the
lock nut 454 on the threaded shaft 452, the user can adjust the
position of the inner tube 402 relative to the outer tube 404 to
increase or decrease the length of the occlusion balloon 410 when
inflated. The sliding fluid seal 440 may be a Tuohy-Borst adapter
as described above or, because a separate locking mechanism 450 is
provided, it may be a simple sliding seal, such as an O-ring or
wiper seal 456, as illustrated.
[0123] When the balloon 410 is deflated the inner tube 402 can be
moved to its furthest distal position and locked with respect to
the outer tube 404, as shown in FIG. 6A. This stretches the wall of
the occlusion balloon 410 collapsing the deflated balloon tightly
around the inner tube 402 to reduce the deflated profile for easy
introduction through the peripheral arterial access site or through
an introducer sheath. Once the occlusion balloon 410 has been
advanced to the desired location in the ascending aorta, the
locking mechanism 440 can be released so that the balloon 410 can
be inflated. FIG. 6B shows the endoaortic partitioning catheter 400
of FIG. 1A with the inner tube 402 in an intermediate position with
respect to the outer tube 404 and the occlusion balloon 410'
inflated. In this position, the inner tube 402 and the outer tube
404 keeps a tension on the ends of the occlusion balloon 410' which
elongates the balloon somewhat in the axial direction. This results
in the balloon 410' having a somewhat oblong inflated profile which
is smaller in diameter and longer axially than the typical
spherical shape of a freely inflated balloon. FIG. 6C shows the
endoaortic partitioning catheter 400 of FIGS. 1A and 1B with the
inner tube 402 in its farther proximal position with respect to the
outer tube 404 and the occlusion balloon 410" inflated. In this
position, the inner tube 402 and the outer tube 404 places a
compressive force on the ends of the occlusion balloon 410" which
restricts the expansion of the balloon somewhat in the axial
direction. This results in the balloon 410" having an inflated
profile which achieves the full diameter of a freely inflated
balloon diameter, but is somewhat shorter in the axial direction.
This feature allows the user to select the inflated diameter of the
balloon and the axial length of the balloon, and therefore the
length of contact with the aortic wall, within certain ranges, as
well as allowing the balloon to be more fully collapsed when
deflated for insertion and removal. The range of useful balloon
diameters of the occlusion balloon 410 for use in an adult human
ascending aorta is from above 20 to 40 cm. Other ranges of balloon
diameters may be needed for pediatric patients or nonhuman
subjects.
[0124] This feature will find particular utility when the
endoaortic partitioning catheter 400 is used while performing
surgery or other interventional procedures on the aortic valve, or
within the aortic root or ascending aorta. To facilitate the
surgery, it will be important to provide as much clearance as
possible between the inflated occlusion balloon 410" and the aortic
valve to allow manipulation of instruments within the ascending
aorta while at the same time being sure that the occlusion balloon
410" does not occlude the brachiocephalic artery. In this case, the
inner tube 402 would be adjusted to its farthest proximal position
with respect to the outer tube 404 before the occlusion balloon
410" is inflated in order to restrict the size of the balloon 410"
as much as possible in the axial direction.
[0125] FIG. 9A shows a transverse cross section of a
coaxial-construction endoaortic partitioning catheter 500 in which
the inner tube 502 and the outer tube 504 are rotatable with
respect to one another. The inner tube 502 has a cardioplegia
infusion lumen 512 connected to a luer fitting connection 526 on
the proximal hub 508. The outer tube 504 fits coaxially around the
inner tube 502 with an annular space between the two tubes
providing a balloon inflation lumen 516 which communicates with a
luer fitting connection 522 on the proximal hub 508. The outer tube
504 is connected to a rotating collar 540 which is rotatably and
slidably mounted on the distal end of the proximal hub 508. There
is an O-ring seal 542 or other type of fluid tight seal between the
rotating collar 540 and the proximal hub 508. An aortic occlusion
balloon 510 is mounted on the distal end of the catheter 500 with
the proximal balloon neck 518 sealingly attached to the outer tube
504 and the distal balloon neck 520 sealingly attached to the inner
tube 502 of the catheter 500 so that the balloon inflation lumen
516 communicates with the interior of the balloon 510. The
occlusion balloon 510 is preferably made of an elastomeric
material, such as latex, silicone or polyurethane. A piezoelectric
distal pressure transducer 530 mounted at the distal tip of the
catheter 500 electronically monitors the aortic root pressure and
transmits a signal along signal wires 532 and 534 to electrical
connections 536 and 538 within an electrical connector 524 on the
proximal hub 508 of the catheter 500.
[0126] In order to collapse the occlusion balloon 510 to its lowest
possible deflated profile for introduction or withdrawal of the
catheter 500 through a peripheral arterial access site or through
an introducer sheath, the rotating collar 540 can be rotated with
respect to the proximal hub 508 to twist the deflated occlusion
balloon 510 around the inner tube 502. In addition, the rotating
collar 540 can also be moved proximally with respect to the
proximal hub 508 to tension the balloon to create an even lower
deflated profile. After the catheter has been introduced and
maneuvered to the desired position, the rotating collar 540 is
counter rotated to release the balloon from its twisted state
before inflation. The catheter 500 with the fully inflated
occlusion balloon 510' is shown in FIG. 9B. When the catheter is to
be withdrawn after use, the occlusion balloon 510 is deflated and
the rotating collar 540 is again rotated and moved proximally with
respect to the proximal hub 508 to twist the deflated occlusion
balloon 510 around the inner tube 502 to create a lower deflated
profile for removal of the catheter 500.
[0127] In each of the previously described embodiments, the shaft
of the catheter, whether it has a coaxial construction or a
multilumen construction, may take one of a variety of forms. In the
simplest form, the shaft of the catheter may be a straight length
of flexible tubing, made from a highly flexible plastic or
elastomer, such as polyurethane, polyethylene, polyvinylchloride or
a polyamide polyether block copolymer, preferably in the range of
35 to 72 Shore D durometer. Another variation of this embodiment
would be to provide a straight shaft with zones of varying
stiffness graduated from a stiff proximal section to a highly
flexible distal section. The variable stiffness shaft could be made
by welding tubing segments of different stiffness polymers
end-to-end to create two, three or more zones of stiffness. In one
illustrative embodiment, the catheter shaft could be made with a
stiff proximal section of a polyamide polyether block copolymer
with a hardness of 63 to 72 Shore D durometer, an intermediate
section of a softer grade of the same polymer with a hardness of 55
to 63 Shore D durometer, and a distal section of a very soft grade
of the polymer with a hardness of 35 to 55 Shore D durometer. In
addition, an especially flexible soft tip with a hardness of 25 to
35 Shore D durometer may be molded or heat bonded to the distal end
of the catheter shaft. Alternatively, the shaft can be made with
continuously graduated stiffness from the proximal to distal end
using a process such as total intermittent extrusion to gradually
change the stiffness along the length of the catheter shaft. In a
coaxial-construction catheter either or both of the inner tube and
the outer tube may be made with varying stiffness to achieve the
overall effect of a graduated stiffness catheter. Furthermore,
either or both of the inner tube and the outer tube may be
reinforced with wire or filament braiding or coils for increased
stiffness, torque control or kink resistance.
[0128] The polymeric material of the shaft is preferably loaded
with a radiopaque filler, such as bismuth subcarbonate, bismuth
oxychloride, bismuth trioxide, barium sulfate or another radiopaque
material. The shaft is preferably loaded with a level of between
about 10 and 30 percent of radiopaque filler by weight, preferably
about 20%. The soft tip may be loaded with a higher percent of
radiopaque filler, such as about 30 to 35 percent by weight for
greater fluoroscopic visibility. Instead of or in addition to the
radiopaque filler, radiopaque markers, for example rings of gold,
platinum, tin, tantalum or tungsten alloys may be attached to the
catheter shaft at various points along the length, especially at
the tip of the catheter for fluoroscopic visibility.
[0129] In such an embodiment, the highly flexible catheter would be
advanced through the patient's descending aorta and into the
ascending aorta with a stiffer guidewire and/and or a dilator
placed in the infusion lumen of the catheter to provide stiffness
for advancing and maneuvering the catheter into position. With the
varying stiffness embodiment, the stiffness of the proximal shaft
segment will assist in advancing and maneuvering the catheter into
position. If desired, a curved guidewire or dilator may be used to
assist in forming the catheter shaft to the curve of the aortic
arch. Once the catheter is in position, the balloon would be
inflated to occlude the ascending aorta and the guidewire or
dilator withdrawn to free the infusion lumen for infusing
cardioplegic fluid.
[0130] In another approach, the catheter shaft may be made of a
somewhat stiffer polymer so that the distal segment of the catheter
can be precurved to a configuration that assists in maneuvering the
occlusion balloon into the correct position within the ascending
aorta. As with the straight catheter shaft previously described,
the precurved catheter shaft may also be made with varying degrees
of stiffness graduated from a stiff proximal segment to a flexible
distal segment. The shaft would be made of slightly higher
durometer grades of a flexible plastic or elastomer, such as
polyurethane, polyethylene, polyvinylchloride or a polyamide
polyether block copolymer, preferably in the range of 55 to 72
Shore D durormeter. A short, very flexible tip of a low durometer
polymer, preferably in the range of 25 to 35 Shore D durometer, can
be added to the distal end to make it less traumatic to the
arterial walls and the aortic valve which it may come in contact
with. Two variations of precurved catheter shafts are shown in
FIGS. 10A-10C and 11A-11C. For the purposes of illustration, these
embodiments are shown as built in a multilumen construction, but
the precurved shafts can as well be made in one of the coaxial
constructions previously described.
[0131] One preferred embodiment of an aortic partitioning catheter
600 with a precurved shaft is shown in FIG. 10A. In this embodiment
the distal portion 604 of the catheter shaft 602 is configured to
facilitate placement of the occlusion balloon 610 into the
ascending aorta. The curve of the catheter shaft 602 also
stabilizes the catheter in the proper position to prevent migration
or dislodgement of the inflated occlusion balloon. The distal
portion 604 of the catheter shaft 602 has a curve of approximately
270-300 degrees of arc. The curve of the catheter shaft 602 is a
compound curve having a first segment 606 of approximately
135.degree. of arc with a radius of curvature of approximately
75-95 mm. Contiguous with the first segment is a second segment 608
of approximately 135.degree. of arc with a tighter radius of
curvature of approximately 40-50 mm. Continuing from the second
segment is a third segment 612 of approximately 25-50 mm in length
adjacent to the distal end 614 of the catheter. The occlusion
balloon 610 is mounted on the third segment 612 of the catheter
shaft near the distal end 614 of the catheter 600. The third
segment 612 of the catheter 600 may be straight, so that the total
arc subtended by the catheter curve 604 is approximately
270.degree.. Alternatively, the third segment 612 of the catheter
600 may be angled upward at a point about midway along the third
segment 612, as shown in FIG. 10A, creating a total arc of
curvature of about 300.degree.. The upward angle of the third
segment 612 helps the catheter 600 to follow a dilator or guidewire
as it passes over the curve of the aortic arch during catheter
introduction. The angle of the third segment 612 also helps to
prevent the distal tip 614 of the catheter 600 from contacting the
interior wall of the aorta as it passes over the aortic arch
thereby reducing the likelihood of irritating or damaging the
aortic wall or of dislodging calculi or other sources of potential
emboli. The curve of the catheter is generally coplanar, as shown
in the side view in FIG. 10B. The specifics of this catheter curve
are given as an illustrative example of one preferred embodiment.
The precise angles and lengths of the curve may be varied according
to the geometry of the patient's anatomy based on fluoroscopic
observation of the aortic arch.
[0132] A cross section of the catheter shaft is shown in FIG. 10C.
The catheter shaft 602 is made from a multilumen extrusion of a
flexible plastic or elastomer, such as polyurethane, polyethylene,
polyvinylchloride or a polyamide polyether block copolymer,
preferably in the range of 55 to 72 Shore D durometer. In one
preferred embodiment, the multilumen catheter shaft 602 has a
cardioplegia infusion lumen 616, a distal pressure monitoring lumen
618, and a balloon inflation lumen 620. The balloon inflation lumen
620 is in fluid communication with the interior of the inflatable
occlusion balloon 610. The infusion lumen 616 and the distal
pressure monitoring lumen 618 each connect with separate ports at
or near the distal tip 614 of the catheter 600, distal to the
occlusion balloon 610. For use with blood/cardioplegia techniques,
the catheter shaft 602 preferably has an external diameter of 3.5
to 4 mm or 10.5 to 12 French (Charrire scale). For use with
crystaloid cardioplegia techniques, the catheter shaft 602 may be
made smaller, with an external diameter of 3.3 mm or 10 French
(Charri{fraction (e)}re scale) or smaller.
[0133] FIG. 11 is a schematic partly cut-away representation of a
patient's aortic arch A with the endoaortic partitioning catheter
600 of FIG. 10A positioned in the ascending aorta B. In use, the
distal curve 604 in the catheter shaft 602 of FIG. 10A is initially
straightened out by inserting a guidewire and a dilator (not shown)
into the infusion lumen 616 of the catheter 600 to facilitate
insertion of the catheter 600 into a peripheral arterial access
site such as the femoral artery. The catheter 600 is advanced until
the distal end 614 of the catheter 600 is at the apex of the aortic
arch A. Then, the dilator is withdrawn as the catheter 600 is
advanced over the aortic arch A to allow the curved distal portion
604 of the catheter 600 to resume its curve within the ascending
aorta B. When the catheter 600 is in proper position in the
ascending aorta B, the second segment 608 of the curved shaft
conforms to the aortic arch A to hold the distal tip 614 of the
catheter centered just above the aortic root R. The first curved
segment 606 of the catheter shaft resides in the descending aorta
D, somewhat straightened by its contact with the aortic walls. If
the patient has a relatively straight ascending aorta B, as
observed fluoroscopically, a straight third segment 612 of the
curved shaft is preferred for proper centering of the catheter tip
614 when the occlusion balloon 610' is inflated. If the ascending
aorta B is curved, a curved or angled distal segment 612, such as
the one illustrated in FIG. 10A, is preferred.
[0134] Another preferred embodiment of an aortic partitioning
catheter 650 with a precurved shaft is shown in FIG. 12A. In this
embodiment also the distal portion 654 of the catheter shaft 652 is
configured to facilitate placement of the occlusion balloon 660
into the ascending aorta and to stabilize the catheter in the
proper position to prevent migration or dislodgement of the
inflated occlusion balloon 660', but with a slightly different
geometry to accommodate variations in the patient's anatomy. The
distal portion 654 of the catheter shaft 652 has an approximately
elliptical curve which subtends approximately 270-300 degrees of
arc. The minor axis 646 of the ellipse is parallel to the shaft 652
of the catheter and has a length of about 50 to 65 mm. The major
axis 648 of the ellipse is perpendicular to the shaft 652 of the
catheter and has a length of about 55 to 70 mm. The elliptical
curve can also be viewed as having a first segment 656 with a
larger radius of curvatures a second segment 658 with smaller
radius of curvature and a third segment 662 on which the occlusion
balloon 660 is mounted. The curved distal portion 654 of the
catheter 650 is somewhat out of plane with the catheter shaft,
angling or spiraling anteriorly from the plane of the catheter
shaft by about 10-20.degree., as shown in FIG. 12B. In one
presently preferred embodiment, the distal tip 664 of the catheter
650 has an offset 672 from the plane of the catheter shaft 652 of
approximately 14 mm. The offset 672 of the spiral curve helps to
center the catheter tip 664 within the ascending aorta in patients
in whom the ascending aorta is angled anteriorly. The preferred
degree of offset 672 can vary significantly depending on patient
anatomy, with an anticipated range of from 0 to 25 mm of offset 672
to accommodate most patients. Again, this catheter curve is given
as an example of one preferred embodiment. The precise angles and
lengths of the curve should be chosen according to the geometry of
the patient's anatomy based on fluoroscopic observation of the
aortic arch. Providing the catheters in a family of curves which
are variations of the curves shown in FIGS. 10A and 12A, etc. will
allow the user to select the proper catheter curve for the patient
after observing the geometry of the aorta fluoroscopically.
[0135] A cross section of the catheter shaft is shown in FIG. 12C.
The catheter shaft 652 is made from a multilumen extrusion of a
flexible plastic or elastomer, such as polyurethane, polyethylene,
polyvinylchloride or a polyamide polyether block copolymer,
preferably in the range of 55 to 72 Shore D durometer. In this
illustrative embodiment, the multilumen catheter shaft 652 has a
cardioplegia infusion lumen 666, a distal pressure monitoring lumen
668, and a balloon inflation lumen 670. The balloon inflation lumen
670 is in fluid communication with the interior of the inflatable
occlusion balloon 660. The infusion lumen 666 and the distal
pressure monitoring lumen 668 each connect with separate ports at
or near the distal tip of the catheter 664, distal to the occlusion
balloon 660. The catheter shaft 652 can be made in a range of
sizes, for instance with an external diameter of 3.5 to 4 mm or
10.5 to 12 French (Charrire scale) for use with blood/cardioplegia
techniques, or with an external diameter of 3.3 mm or 10 French
(Charrire scale) or smaller for use with crystaloid cardioplegia
techniques.
[0136] FIG. 13 is a schematic partly cut away representation of a
patient's aortic arch A with the endoaortic partitioning catheter
650 of FIG. 12A positioned in the ascending aorta B. In use, a
guidewire and a dilator (not shown) are inserted into the infusion
lumen 666 to straighten out the distal curve 654 of the catheter
650. The catheter 650 is introduced into a peripheral arterial
access site such as the femoral artery and advanced until the
distal end 664 of the catheter 650 is at the apex of the aortic
arch A. Then, the dilator is withdrawn as the catheter is advanced
over the aortic arch A to allow the distal portion 652 of the
catheter 650 to resume its curve within the ascending aorta B. When
the catheter 650 is in proper position in the ascending aorta B,
the second segment 658 of the curved shaft conforms to the aortic
arch A to hold the distal tip 664 of the catheter centered just
above the aortic root R. Due to its curvature, the second segment
658 of the catheter shaft tends to hug the inside curve of the
aortic arch A which helps to prevent the catheter shaft from
occluding or interfering with blood flow into the brachiocephalic
artery or other arteries which have their takeoff from the aortic
arch. The first curved segment 656 of the catheter shaft 652
resides in the descending aorta D, somewhat straightened by its
contact with the aortic walls. The angled or spiral curve of the
catheter shaft 652 assists in centering the distal tip 664 of the
catheter 650 within the lumen of the ascending aorta B which is
often angled anteriorly within the patient.
[0137] In order to reduce the external diameter of the catheter
shaft in the embodiments of FIGS. 10A-10C and 12A-12C, particularly
for use in conjunction with the dual purpose arterial cannula and
introducer sheath described below in reference to FIGS. 31-34,
while maintaining the maximum flow rate performance in the
catheter, it is desirable to reduce the wall thickness of the
multilumen extrusion as much as possible. In order to improve the
kink resistance of the thin-walled catheter shaft in the precurved
distal portion (604 in FIG. 10A, 654 in FIG. 12A) it has been found
to be advantageous to dip coat the precurved distal portion with a
soft, flexible polymer. For example a coating approximately
0.005-0.020 inches thick of a polyurethane with a hardness of 80
Shore A durometer on the precurved distal portion of the catheter
shaft has been shown to significantly improve the kink resistance
of the catheter shaft. If the coating is applied before mounting
the polyurethane occlusion balloon on the catheter shaft, the
coating also improves the heat bondability of the occlusion balloon
to the shaft. Coating only the distal portion of the catheter shaft
has the advantage that it does not increase the external diameter
of the catheter shaft in the proximal portion which will reside
within the blood flow lumen of the dual purpose arterial cannula
and introducer sheath during perfusion. Since the proximal portion
of the catheter shaft is not precurved and because it resides in
the relatively straight descending aorta during use, it is not
necessary to fortify the kink resistance of the shaft in this
region.
[0138] One important function of the catheter curves shown in FIGS.
10A and 12A is for centering the tip of the catheter within the
ascending aorta before and after the occlusion balloon is inflated
to insure even distribution of the cardioplegic fluid to the
coronary arteries when it is injected through the infusion lumen
into the aortic root. In many cases, the compound curve of the
catheter is needed to maintain the catheter tip within the center
of the aortic lumen. It has been found that in some cases a simple
180.degree. U-shaped curve results in off-center placement of the
catheter tip despite the concentricity of the inflated balloon
because of the curve of the ascending aorta. Another approach to
centering the distal tip of the catheter within the lumen of the
ascending is illustrated by the embodiment of the aortic
partitioning catheter 700 shown in FIG. 14.
[0139] FIG. 14 is a front view of an embodiment of the endoaortic
partitioning catheter 700 having an eccentric aortic occlusion
balloon 710. The occlusion balloon has a symmetrical deflated
profile, shown by solid lines 710. The asymmetrical inflated
profile, shown by phantom lines 710', is achieved by molding the
occlusion balloon with a thicker wall 712 on one side of the
balloon 710. The thicker wall 712 of the balloon is oriented toward
the inside of the distal curve 704 when mounted on the catheter
shaft 702. When the occlusion balloon 710' is inflated, the thicker
wall 712 resists expansion while the thinner wall 714 of the
balloon more easily expands to its full potential, resulting in the
intended eccentric inflated balloon profile 710'. One preferred
method for manufacturing the occlusion balloon 710 of FIG. 14 is by
a two-stage dip molding process. In the first stage of the process,
a balloon mold, in the form of a dipping mandrel having the desired
interior shape of the balloon, is oriented vertically and dipped
into a solution or a suspension containing an elastomeric balloon
material, such as polyurethane, silicone or latex. This creates a
relatively even coating of the balloon material over the surface of
the mandrel. This first coating 706 is then allowed to dry on the
mandrel. Once the first coating 706 is dry, the orientation of the
dipping mandrel is rotated to a horizontal position and one side of
the balloon mandrel is dipped into the elastomer solution to create
a second coating 708 of balloon material on one side of the balloon
710. The balloon mandrel is held in the horizontal orientation
until the solvent evaporates from the elastomer solution. If the
elastomer used to mold the balloon 710 is a thermoplastic
elastomer, such as a thermoplastic polyurethane, the balloon can be
removed from the dipping mandrel once it has dried. If the
elastomer is a thermoset material, such as latex, silicone, or a
thermoset polyurethane, further curing of the material may be
required before the balloon 710 can be removed from the dipping
mandrel. It should be noted that the second coating 708 on the
balloon 710 may be made of a different material from the first
coating 706. For instance, a stronger or less distensible material
may be used for the second coating 708 to increase the resistance
of the thicker wall 712 of the balloon 710 to inflation. It should
also be noted that molding each coating of the balloon may require
multiple iterations of the dipping and drying steps, depending on
the composition and concentration of the polymer solution. For
example, the currently preferred process for manufacturing
polyurethane balloons typically requires about 6-8 iterations of
the dipping and drying steps to make a finished balloon with a wall
thickness of approximately 0.005-0.020 inches.
[0140] FIGS. 15 and 16 illustrate how an eccentric balloon, like
the eccentric occlusion balloon 710 of the catheter embodiment of
FIG. 14, operates to center the tip of the aortic partitioning
catheter within the ascending aorta of a patient. FIG. 15 is a
schematic partly cut-away representation of a patient's aortic arch
A with an endoaortic partitioning catheter 720 having a concentric
occlusion balloon 722 positioned in the ascending aorta B. The
endoaortic partitioning catheter 720 has a 180.degree. U-shaped
catheter curve 724 with a concentric occlusion balloon 722 mounted
on a straight distal portion 726 of the catheter 720. FIG. 15 shows
the effect of placing the U-shaped catheter curve into a patient
having a curved ascending aorta B. Note how, when the catheter 720
is pulled proximally to stabilize the catheter within the aortic
arch A, the distal end 728 of the catheter is not centered in the
aortic lumen despite the concentricity of the balloon 722 because
of the mismatch between the catheter curve and the curve of the
ascending aorta B.
[0141] FIG. 16 is a schematic partly cut-away representation of a
patient's aortic arch A with an endoaortic partitioning catheter
730 having an eccentric occlusion balloon 732 positioned in the
ascending aorta B. The aortic partitioning catheter 730 has a
U-shaped distal curve 734 which subtends an arc of approximately
180.degree.+/-45.degree.. Mounted on a straight distal portion 736
of the catheter shaft is an occlusion balloon 732 which, when
inflated, has an eccentric balloon profile with the larger portion
740 of the balloon facing the outside of the catheter curve 734 so
that it will be oriented toward the right side of the patient. The
eccentric inflated profile of the balloon 732 assists in centering
the distal tip 738 of the catheter 730 within the aortic lumen when
the ascending aorta B is curved. Note how the eccentric balloon 732
compensates for the mismatch between the catheter curve and the
curve of the ascending aorta B to result in the distal tip 738 of
the catheter 730 being well centered in the aortic lumen just above
the aortic root R.
[0142] FIG. 17 shows an alternative construction for an occlusion
balloon 742 with an eccentric inflated profile 742'. In this
embodiment, the elastomeric balloon 742 is molded on a dipping
mandrel which is machined with an asymmetrical profile. In contrast
to the previous example, the molded balloon 742 has a uniform wall
thickness, but it has an asymmetrical deflated profile with a
larger side 744 and a smaller side 746. The balloon 742 is mounted
on the catheter with the larger side 744 oriented toward the
outside of the distal curve 748 of the catheter 750. When inflated,
the larger side 744 of the balloon expands to a greater radius 744'
than the smaller side 746', giving the intended eccentric inflated
profile, as shown by phantom lines 742'.
[0143] FIGS. 18A and 18B show another alternative construction for
an occlusion balloon 752 with an eccentric inflated profile 752'.
In this embodiment, the elastomeric occlusion balloon 752 is
mounted on the catheter 760 in such a way that the side 754 of the
balloon oriented toward the inside of the distal curve 758 of the
catheter is bonded directly to the catheter shaft 756 along the
length of the balloon 752 using a suitable adhesive. When the
occlusion balloon 752 is inflated, only the side of the balloon
oriented toward the outside of the distal curve 758 of the catheter
shaft is allowed to expand, creating an eccentric inflated balloon
profile, as shown by phantom lines 752'.
[0144] FIGS. 19A-19D and 20A-20D show alternative constructions of
an eccentric occlusion balloon made of a nondistensible balloon
material, such as polyethylene, polyethylene terephthalate
polyester, polyester copolymers, polyamide or polyamide copolymers.
Using a nondistensible balloon material such as these allows more
precise control over the final shape and dimensions of the inflated
occlusion balloon, as compared to the elastomeric balloons
previously described. The nondistensible balloons can be
thermoformed from tubing extruded from a nonelastomeric polymer,
using known methods. Alternatively, the balloons can be dipped or
rotomolded of a nonelastomeric polymer in solution. It is presently
preferred to mold the inelastic balloon material using a hollow or
negative mold of the exterior inflated balloon shape rather than a
positive mold of the interior shape as used for the elastomeric
balloons, because the molded inelastic balloons may be difficult to
remove from a positive mold.
[0145] FIGS. 19A-19D show a first example of a nondistensible
eccentric occlusion balloon 762. FIG. 19A shows a side view of the
occlusion balloon in the deflated state 762 and inflated state
762'. FIG. 19B shows an end view of the same occlusion balloon in
the deflated 762 and inflated states 762'. The occlusion balloon
762 is molded in an asymmetrical shape with a large side 764 and a
smaller side 766. The occlusion balloon 762 is mounted on the
catheter shaft 768 with the larger side 764 oriented toward the
outside of the distal curve of the catheter. The occlusion balloon
tends to flatten out, as shown by solid lines 762, when it is
deflated. In order to reduce the deflated profile of the balloon
for introduction into a peripheral artery, the flattened balloon
762" is wrapped around the catheter shaft 768 as shown in a side
view in FIG. 19C and an end view in FIG. 19D.
[0146] FIGS. 20A-20D show a second example of a nondistensible
eccentric occlusion balloon 780. FIG. 20A shows a side view of the
occlusion balloon in the deflated state 780 and inflated state
780'. FIG. 20B shows an end view of the same occlusion balloon in
the deflated state 780 and inflated state 780'. The occlusion
balloon 780 is molded in an asymmetrical shape with a large side
782 and a smaller side 784. The occlusion balloon 780 is mounted on
the catheter shaft 786 with the larger side 782 oriented toward the
outside of the distal curve of the catheter. In this embodiment,
the smaller side 784 of the occlusion balloon is adhesively bonded
to the catheter shaft 786 along the length of the balloon 780 so
that the inflated balloon 780' expands only toward the outside of
the distal curve of the catheter. The occlusion balloon flattens
out, as shown by solid lines 780, when it is deflated. In order to
reduce the deflated profile of the balloon for introduction into an
artery, the flattened balloon 780" is wrapped around the catheter
shaft as shown in a side view in FIG. 20C and an end view in FIG.
20D.
[0147] The eccentrically shaped occlusion balloons of FIGS. 14 and
16-20 serve to help center the distal tip of the aortic
partitioning catheter within the ascending aorta for uniform
distribution of cardioplegic fluid injected through the infusion
lumen and for aligning the tip of the catheter with the center of
the aortic valve when other instruments are introduced through the
infusion lumen. The degree of concentricity of the occlusion
balloon can be varied from perfectly concentric to completely
eccentric, or one-sided, using the embodiments and methods
described in connection with FIGS. 14 and 16-20. Specially shaped
occlusion balloons can also be used with the aortic partitioning
catheter of the present invention for maximizing the working space
within the ascending aorta between the aortic valve and the
occlusion balloon. This aspect of the invention will be of
particular significance when the catheter system is used for
arresting the heart so that surgery or other interventional
procedures can be performed on the patient's aortic valve. Whether
the aortic valve surgery is performed by thoracoscopic methods,
endovascular methods or open chest surgical methods, it will be
beneficial to be able to occlude the ascending aorta as required
for establishing cardiopulmonary bypass without obstructing
surgical access to the aortic valve. This aspect of the invention
will also find particular utility when performing port-access CABG
surgery with a saphenous vein bypass graft or other free graft
which must be anastomosed to the ascending aorta because the
occlusion balloon will not interfere with the anastomosis
procedure. FIGS. 21-24 show four variations of specially shaped
balloons developed for this purpose. These balloons can be
manufactured from elastomeric materials or from nondistensible,
inelastic materials as previously described.
[0148] FIG. 21 is a schematic partly cut-away representation of a
patient's aortic arch A with a first variation of an endoaortic
partitioning catheter 790 having a shaped occlusion balloon 792
positioned in the ascending aorta B. The occlusion balloon 792 has
a generally cylindrical outer geometry that has been modified by
curving it to match the curvature of the aortic arch A. Thus, the
surface of the occlusion balloon facing the outside curve of the
aortic arch A has a convex curvature 794 to match the concave
curvature of the aortic wall at that point and the surface of the
occlusion balloon facing the inside curve of the aortic arch A has
a concave curvature 796 to match the convex curvature of the
opposite aortic wall. The geometry of the occlusion balloon 792 is
further modified by molding a groove or indentation 798 into the
proximal edge of the convexly curved outer surface 794 of the
balloon 792. The indentation 798 is positioned to allow blood flow
past the occlusion balloon 792 into the brachiocephalic artery C.
This allows the occlusion balloon 792 of the aortic partitioning
catheter 790 to be placed as far downstream in the ascending aorta
as possible without occluding flow to the brachiocephalic artery C
from the cardiopulmonary bypass system. The working space between
the aortic valve V and the occlusion balloon 792 is maximized to
allow maneuvering of surgical instruments, interventional catheters
or a valve prosthesis within the ascending aorta B. Although it
does not serve to occlude the aortic lumen, the proximal portion of
the occlusion balloon 792 contacts the aortic wall and helps to
stabilize the inflated balloon within the aorta to keep the distal
end of the catheter centered and to help prevent unintended
displacement of the inflated balloon.
[0149] FIG. 22 is a schematic partly cut-away representation of a
patient's aortic arch A with a second variation of an endoaortic
partitioning catheter 800 having a shaped occlusion balloon 802
positioned in the ascending aorta B. As in the previous example,
the occlusion balloon 802 has a generally cylindrical outer
geometry that has been modified by curving it to match the
curvature of the aortic arch A. The surface of the occlusion
balloon facing the outside curve of the aortic arch A has a convex
curvature 804 to match the concave outer curvature of the aortic
wall and the surface of the occlusion balloon facing the inside
curve of the aortic arch A has a concave curvature 806 to match the
convex inner curvature of the opposite aortic wall. The geometry of
the occlusion balloon 802 is further modified by molding a large
ramp-shaped indentation 808 into the proximal side of the convexly
curved outer surface 804 of the balloon 802. The wall of the
occlusion balloon 802 can be adhesively attached to the catheter
shaft 810 along the length of the ramp-shaped indentation 808 to
help maintain the geometry of the balloon when subjected to
inflation pressure. The ramp-shaped indentation 808 is positioned
to allow blood flow past the occlusion balloon 802 into the
brachiocephalic artery C. This allows the occlusion balloon 802 of
the aortic partitioning catheter 800 to be placed as far downstream
in the ascending aorta as possible without occluding flow to the
brachiocephalic artery C in order to maximize the working space
between the aortic valve V and the occlusion balloon 802. The broad
ramp-shaped indentation 808 in the occlusion balloon 802 lessens
the need for careful placement of the occlusion balloon 802 with
respect to the brachiocephalic artery C without danger of occluding
it. The concavely curved inner surface 806 of the occlusion balloon
802 provides an extended contact surface with the wall of the
aortic arch A to stabilize the inflated occlusion balloon 802 and
to discourage unintended movement or dislodgement of the occlusion
balloon 802. As in the previous embodiment, the proximal portion of
the occlusion balloon 802 contacts the aortic wall and helps to
stabilize the inflated balloon within the aorta to keep the distal
end of the catheter centered and to help prevent unintended
displacement of the inflated balloon.
[0150] FIG. 23A is a schematic partly cut-away representation of a
patient's aortic arch A with a third variation of an endoaortic
partitioning catheter 820 having a shaped occlusion balloon 812
positioned in the ascending aorta B. FIG. 23B is a transverse cross
section of the shaped occlusion balloon of FIG. 23A. This occlusion
balloon 812 also has a generally cylindrical outer geometry that
has been modified by curving it to match the curvature of the
aortic arch A. The surface of the occlusion balloon facing the
outside curve of the aortic arch A has a convex curvature 814 to
match the concave outer curvature of the aortic wall and the
surface of the occlusion balloon facing the inside curve of the
aortic arch A has a concave curvature 816 to match the convex inner
curvature of the opposite aortic wall. The geometry of the
occlusion balloon 812 is further modified by molding an extended
groove or invagination 818 into the proximal side of the convexly
curved outer surface 814 of the balloon 812. The extended groove
818 should have a width at least as wide as the ostium of the
brachiocephalic artery C. The wall of the occlusion balloon 812 can
be adhesively attached to the catheter shaft 822 along the length
of the extended groove 818 to help maintain the geometry of the
balloon when subjected to inflation pressure. The extended groove
818 is positioned to allow blood flow past the occlusion balloon
812 into the brachiocephalic artery C. This allows the occlusion
balloon 812 of the aortic partitioning catheter 800 to be placed
even farther downstream in the ascending aorta without occluding
flow to the brachiocephalic artery C in order to maximize the
working space between the aortic valve V and the occlusion balloon
812. Again, the concavely curved inner surface 816 of the occlusion
balloon 812 provides an extended contact surface with the wall of
the aortic arch A to stabilize the inflated occlusion balloon 812
and to discourage unintended movement or dislodgement of the
occlusion balloon 812.
[0151] FIG. 24 is a schematic partly cut-away representation of a
patient's aortic arch A with a fourth variation of an endoaortic
partitioning catheter 824 having a shaped occlusion balloon 826
positioned at the apex of the aortic arch A. In an effort to
further maximize the working space between the aortic valve V and
the occlusion balloon 826 the geometry of the occlusion balloon 826
has been modified so that it can be placed at the very apex of the
aortic arch A without compromising blood flow to the
brachiocephalic, common carotid or subclavian arteries. The
occlusion balloon 826 has a generally cylindrical outer geometry
modified with a helical groove 830 that starts at the proximal end
834 of the balloon and spirals around the balloon 826 in the distal
direction. In this illustrative embodiment, the spiral groove 830
forms approximately two complete turns encircling the occlusion
balloon 826 and is delimited by an annular ring 828 that forms a
seal with the aortic wall at the distal end of the balloon 826 to
isolate the heart and the coronary arteries the systemic blood flow
which is supported by the cardiopulmonary bypass system. The spiral
groove 830 forms a flow path for oxygenated blood from the
descending aorta to the brachiocephalic, common carotid or
subclavian arteries C. A spiral ridge 832 that runs along the
spiral groove 830 contacts the aortic wall and stabilizes the
inflated occlusion balloon 826 to prevent unintended movement of
the occlusion balloon 812 without occluding blood flow to the head
and neck arteries. This same effect can be accomplished using
functionally equivalent balloon geometries. For instance, this
effect could be achieved with a shaped balloon having an annular
ring at the distal end of the balloon to seal against the aortic
wall, isolating the heart and the coronary arteries from systemic
blood flow, and a multiplicity of bumps or ridges at the proximal
end to contact the aortic wall and stabilize the balloon, with the
space between the bumps providing a blood flow path to the head and
neck arteries branching from the aortic arch.
[0152] Another aspect of the present invention is illustrated in
FIGS. 25A and 25B. In this embodiment, the function of de-airing
the heart and the ascending aorta at the completion of the
interventional procedure has been combined with the endoaortic
partitioning catheter 130. The catheter 130 is configured so that
the distal tip 131 of the catheter is positioned near the anterior
wall of the ascending aorta B. This can be accomplished by making a
curve 132 in the distal portion of the catheter shaft that brings
the tip 131 of the catheter near the anterior wall of the ascending
aorta B, as shown in FIG. 25A. Alternatively, the occlusion balloon
134 can be shaped so that when the balloon 134 is inflated, the
distal tip 135 of the catheter 133 is directed toward the anterior
wall of the ascending aorta B, as shown in FIG. 25B. The advantage
of this modification of the endoaortic partitioning catheter is
that, when the patient is placed in a supine position, the distal
tip of the catheter is at the highest point in the ascending aorta
so that any air bubbles that enter the heart, the coronary arteries
or the aortic root during the course of surgery can be vented out
through a lumen in the catheter prior to deflating the occlusion
balloon to reverse the cardioplegic arrest.
[0153] FIG. 26 shows another application of shaped balloons for the
purpose of centering the tip 137 of the endoaortic partitioning
catheter 136 within the ascending aorta B. The expandable occlusion
balloon 138 has a distal occlusion means 139 with an expanded
diameter sufficient to occlude the ascending aorta B and a proximal
stabilizing means 140 with an expanded diameter sufficient to
contact the inner surface of the ascending aorta B. Between the
occlusion means 139 and the stabilizing means 140 is an area of
reduced diameter 141. When expanded, the occlusion means 139 blocks
substantially all systolic and diastolic blood flow through the
ascending aorta B. The stabilizing means 140 contacts the inner
surface of the ascending aorta B and orients the distal segment 142
of the catheter shaft so that it is parallel with the axis of the
ascending aorta B, reliably centering the catheter tip 143 within
the aortic lumen just superior to the aortic root R.
[0154] One particular embodiment for achieving this geometry is
shown in FIG. 26. In this embodiment, the occlusion balloon 138 has
a dumbbell shape when expanded. The occlusion means is provided by
a distal lobe 139 of the dumbbell shaped balloon 138, and the
stabilizing means is provided by a proximal lobe 140 of the
balloon, with a waist 141 of reduced diameter between the proximal
140 and distal 139 lobes. The dumbbell shaped occlusion balloon 138
thus has two rings of contact with the inner surface of the
ascending aorta B for better stabilization and orientation of the
balloon in the proper position. Additional advantages of this
configuration are that by providing two rings of contact with the
inner surface of the ascending aorta B, the dumbbell shaped balloon
138 can achieve a better and more reliable seal and greater
resistance to displacement of the inflated balloon.
[0155] Another particular embodiment for achieving a similar
geometry would have two separate, but closely spaced, expandable
balloons mounted on the distal segment of the catheter shaft. When
expanded, the more distal balloon serves as an occlusion means, and
the more proximal balloon serves as a stabilizing means for
orienting the distal segment of the catheter parallel to the axis
of the aortic lumen. It should be noted that the stabilizing means
need not occlude the ascending aorta. However, for proper effect,
it should contact the inner surface of the ascending aorta at at
least three points around the inner circumference of the ascending
aorta. Thus, the stabilizing means may have other non-spherical
geometries that do not fully occlude the ascending aorta. For
instance, multiple smaller balloons could be mounted
circumferentially around the catheter shaft so that, when the
balloons are inflated, they contact the inner surface of the
ascending aorta at at least three points. Likewise, an expandable,
non-balloon stabilizing means can also be used for contacting the
inner surface of the ascending aorta for stabilizing and orienting
the distal tip of the catheter.
[0156] Another approach to centering the distal tip of the
endoaortic partitioning catheter within the ascending aorta, shown
in FIG. 27, works independently of balloon geometry. In this
embodiment, the distal tip 145 of the endoaortic partitioning
catheter 144 is made steerable by one or more control wires 146,
147 extending from the proximal end of the catheter 144 to the
distal end through one or more lumens in the side wall of the
catheter shaft 148. The distal end of the control wires 146, 147
connect to a rigid ring or other anchoring device embedded in the
wall of the catheter shaft 148 near the distal tip 145 of the
catheter 144. The proximal end of the control wires 146, 147
connect to a control means 149 at the proximal end of the catheter.
For catheters 144 having one degree of freedom (i.e. 1-2 control
wires) in the steerability of the distal tip 145, the control means
149 can be a control knob or lever or similar control device. For
catheters 144 having two degrees of freedom (i.e. 4 or more control
wires) in the steerability of the distal tip 145, the control means
149 can be a joy stick or similar control device. The shaft 148 of
the catheter should be made with a flexible distal segment 150
which is relatively more flexible than the proximal portion of the
catheter shaft 148. This concentrates the deflection of the
catheter shaft in the distal section 150 when one or more of the
control wires 146, 147 are tensioned by the control means 149 to
steer the distal tip 145 of the catheter 144.
[0157] The steering mechanism can be used to deflect the distal tip
145 of the catheter shaft away from the aortic wall as the catheter
is advanced through the aortic arch A and into the ascending aorta
B. This reduces the likelihood of any trauma caused to the aortic
wall by the catheterization and reduces the chances of dislodging
any calcifications or other emboli from the aortic wall as the
catheter 144 passes. Once the catheter 144 is in place in the
ascending aorta B and the occlusion balloon 151 is inflated, the
position of the catheter tip 145 can be verified fluoroscopically
and the steering mechanism used to direct the tip 145 of the
catheter toward the center of the aortic lumen in spite of any
curvature in the ascending aorta B or eccentricities in the
occlusion balloon 151. If any diagnostic or therapeutic instruments
are to be delivered through the inner lumen 152 of the endoaortic
partitioning catheter 144 the steering mechanism can be used for
centering the distal tip 145 of the catheter 144 with respect to
the aortic valve V or for directing the instruments to other
anatomical features within the heart or the aortic root R. The
steering mechanism can also be used for directing the catheter tip
145 toward the anterior wall or the highest point in the ascending
aorta for de-airing the heart and the ascending aorta at the
completion of the interventional procedure before deflating the
occlusion balloon to reverse the cardioplegic arrest, as described
above in relation to FIG. 25.
[0158] Another aspect of the present invention is illustrated in
FIG. 28. In this embodiment, a fiberoptic illumination device 153
has been combined with the endoaortic partitioning catheter 154.
The fiberoptic illumination device 153 can serve two distinct
purposes. The first function of the fiberoptic illumination device
153 can be for transillumination of the aortic wall W for detecting
plaque and calcifications P in the aortic wall and for identifying
the optimal point for creating a proximal anastomosis of a coronary
bypass vein graft. In this embodiment, a fiberoptic bundle 155 is
extended through the shaft 156 of the endoaortic partitioning
catheter 154 to the distal end. The fiberoptic bundle 155 may be
built into the wall of the catheter shaft 156 or a separate
fiberoptic bundle 155 can be removably inserted through the
infusion lumen of the catheter 154. At the distal end of the
fiberoptic bundle 155 is a light diffuser 157 or a means for
directing a broad lateral beam of light. The proximal end of the
fiberoptic bundle is connected to a high intensity source of
visible light 158. When the light beam or diffuse illumination
passes through the wall W of the aorta, calcifications and heavy
atherosclerotic plaque P can be detected as shadows in the aortic
wall W. The exterior of the aorta can be observed with a
thoracoscope inserted through an intercostal access port into the
patient's chest. The light source for the thoracoscope should be
turned off while performing the transillumination so that the light
coming through the aortic wall can be clearly seen. When this
technique is used in open-chest bypass surgery, the lights in the
operating room should be dimmed so that the light coming through
the aortic wall can be seen. A clear, brightly lit section of the
aortic wall W without shadows will indicate a relatively plaque
free area of the aorta suitable for making the distal anastomosis.
If a separate fiberoptic bundle 155 is inserted through the
infusion lumen of the catheter 154, it can be manipulated from
outside of the patient's body to scan the entire ascending aorta B
to find the optimum anastomosis site or to find multiple
anastomosis sites for multi-vessel bypass operations.
[0159] The second function of the fiberoptic illumination device
153 can be for facilitating placement of the endoaortic
partitioning catheter 154 without the need for fluoroscopic
guidance. In this embodiment, a fiberoptic bundle 155 is extended
through the shaft 156 of the endoaortic partitioning catheter 154
to the distal end. Again, the fiberoptic bundle 155 may be built
into the wall of the catheter shaft 156 or a separate fiberoptic
bundle 155 can be removably inserted through the infusion lumen of
the catheter 154. Located at the distal end of the fiberoptic
bundle 155 is a means 157 for directing a narrow lateral beam of
light to create a spot or a 360.degree. ring of light around the
tip of the catheter. The proximal end of the fiberoptic bundle 155
is connected to a high intensity source of visible light 158. When
the endoaortic partitioning catheter 154 is inserted into the
ascending aorta B, the position of the catheter tip can be
determined by the position of the spot or ring of light where it
shines through the aortic wall W. When the endoaortic partitioning
catheter 154 is in the correct position, the occlusion balloon 159
can be inflated and a cardioplegic agent infused to arrest the
heart.
[0160] These two functions of the fiberoptic illumination device
153 can be combined into one device if the optical elements are
chosen to deliver a beam which is a compromise between the broad
beam needed for aortic wall transillumination and the narrow beam
preferred for the catheter location function. Alternatively, an
optical system could be chosen which is selectively capable of
delivering a broad or narrow lateral beam of light.
[0161] In other alternatively embodiments, the occlusion balloon
158 can be illuminated from the interior with the fiberoptic
illumination device 153 to monitor balloon placement, inflation and
migration. The effectiveness of the illumination can be enhanced by
incorporating reflective or fluorescent material in the balloon or
the inflation fluid.
[0162] Being able to detect the precise position of the endoaortic
partitioning catheter 154 without the need for fluoroscopic imaging
has the potential of simplifying the catheter placement procedure
and the equipment needed in the operating room. Other
non-fluoroscopic means for detecting the position of the catheter
tip include placing a metallic or magnetic marker at the tip of the
catheter and using a thoracoscopically placed Hall effect proximity
detector or magnetometer in the chest cavity to detect the position
of the catheter tip through the aortic wall. Another means of
detecting the position of the catheter tip within the ascending
aorta is by ultrasonic imaging. An endoscopic ultrasonic imaging
probe can be introduced through an access port in the chest or a
transoesophageal ultrasound probe can be used. The imaging of the
catheter can be enhanced by placing an echogenic marker near the
tip of the catheter. A material with significantly higher or lower
acoustic impedance than the catheter and the surrounding tissue and
blood can serve as an echogenic marker. For example, a metal ring
with a roughened exterior surface or an air-filled pocket or ring
of closed cell foam mounted on or embedded in the tip of the
catheter will serve as an echogenic marker. The catheter tip can be
observed with ultrasonic imaging as the catheter is advanced into
the ascending aorta to assure proper placement of the occlusion
balloon.
[0163] Another approach for facilitating placement of the
endoaortic partitioning catheter without the need for fluoroscopic
guidance is illustrated in FIG. 29. This embodiment of the
endoaortic partitioning catheter 160 has a second expandable member
161 mounted on the distal end of the catheter distal to the first
expandable occlusion member 162. In a particular embodiment, the
distal expandable member 161 is an inflatable balloon having a
proximal balloon neck 163 which is attached to the catheter shaft
166 and a distal balloon neck 164 which is inverted and attached to
the distal tip 165 of the catheter shaft. When the distal
expandable member 161 is inflated, it expands to surround and
protect the distal tip 165 of the catheter. If an expandable
balloon is used for the first expandable occlusion member 162 the
first 162 and second 161 expandable members can be inflated through
a single inflation lumen within the catheter shaft 166. Preferably,
however a separate second inflation lumen is provided for
individually inflating the distal expandable member 162. The distal
expandable member 162 preferably has a smaller expanded diameter
than the first expandable occlusion member 161 so that it does not
occlude the lumen of the ascending aorta B.
[0164] In operation, the endoaortic partitioning catheter 160 is
inserted and advanced into the descending aorta D. Then, the distal
expandable member 161 is inflated to act as a soft protective
bumper for the distal end 165 of the catheter 160. The catheter 160
can be advanced over the aortic arch A and into the ascending aorta
B with very little concern about causing trauma to the aortic wall
or dislodging any calcifications or other emboli from the aortic
wall as the catheter passes. When the catheter 160 is in the
ascending aorta B, it is advanced slowly until the distal
expandable member 161 comes into contact with the aortic valve V.
The soft cushion provided by the inflated distal expandable member
161 prevents any damage to the aortic valve V. The operator will be
able to feel that the catheter 160 has stopped advancing from the
proximal end of the catheter which is outside of the patient's body
and will know that the first expandable occlusion member 162 is in
proper position in the ascending aorta B between the coronary ostia
and the brachiocephalic artery without the need for fluoroscopic
verification. The first expandable occlusion member 162 can be
inflated to occlude the ascending aorta B and a cardioplegic agent
infused through the perfusion lumen that exits the catheter through
a port 167 distal to the first expandable occlusion member 162.
[0165] FIGS. 30A and 30B are detail drawings of an additional
feature of the invention which is a frictional locking suture ring
900 for use with the endoaortic partitioning catheter. For
indwelling catheters, such as the endoaortic partitioning catheter,
it is often desirable to fasten the catheter to the patient or to
the surgical drapes to prevent undesired migration or dislodgement
of the catheter from its correct position. The frictional locking
suture ring 900 of FIGS. 30A and 30B is provided as part of the
invention to facilitate anchoring the catheter in place to avoid
unintentional movement of the catheter after it has been positioned
in the ascending aorta. Typical suture rings on introducer sheaths,
central venous catheters and other indwelling catheters are located
at a fixed position near the proximal hub of the catheter. This is
generally adequate for catheters where the precise placement of the
distal tip of the catheter is not critical. With the endoaortic
partitioning catheter, however, the precise placement of the distal
tip of the catheter within the ascending aorta is highly critical
and the distance from the point of insertion of the catheter into
the peripheral arterial access site to the ascending aorta is
highly variable from patient to patient. Therefore, a standard,
fixed-position suture ring would be wholly inadequate in the
present application. The frictional locking suture ring of FIGS.
30A and 30B allows the endoaortic partitioning catheter to be
precisely positioned and reliably anchored in place with any
desired length of the catheter shaft inserted at the access
site.
[0166] The frictional locking suture ring 900 is preferably made
from a tube 902 of a resilient, high-tack polymer, preferably an
extrudable or injection moldable thermoplastic elastomer, such as a
thermoplastic polyurethane with a hardness in the range of 70-90
Shore A durometer or Kraton.TM. (Shell Chemical Co.) thermoplastic
elastomer with a hardness of about 40 Shore A durometer. The length
of the tube 902 is typically from 2-3 cm. The internal diameter of
the tube 902 is slightly larger than the external diameter of the
shaft of the endoaortic partitioning catheter 920. In an exemplary
embodiment for use with a 4 mm diameter or 12 French catheter, the
internal diameter of the tube 902 is preferably about 4.5-4.8 mm,
providing a diametrical clearance of approximately 0.5-0.8 mm. The
external diameter of the tube 902 is typically about 6.5-7.0 mm.
There is a longitudinal slot 904 about 1.2-2.0 mm wide through the
side of the tube 902.
[0167] The frictional locking suture ring 900 is placed over the
exterior of the endoaortic partitioning catheter 920 with the shaft
of the catheter running through the lumen of the tube. Because of
the diametrical clearance between the exterior of the catheter 920
and the interior of the tube 902, the suture ring 900 is free to
move along the length of the catheter 920. However, when a suture
906 or other ligature is tied around the suture ring 900, the tube
902 compresses around the exterior of the catheter 920 and the high
friction due to the tackiness of the suture ring material creates a
firm, nonslip grip on the catheter shaft 920. To facilitate
securing the suture 906 to the suture ring 900, a circumferential
groove 908 is provided on the exterior of the tube 902. In the
illustrative embodiment shown in FIGS. 30A and 30B, there are three
circumferential grooves 908 around the tube at positions near the
proximal end, the center and the distal end of the longitudinal
slot 904 to provide places for tying a suture 906 around the suture
ring 900. In an injection molded embodiment of the suture ring 900,
other suture attachment means, such as one or more eyelets, can
easily be provided on the exterior of the tube 902.
[0168] In order to increase the frictional grip between the
frictional locking suture ring 900 and the shaft of the endoaortic
partitioning catheter 920, a strip of high friction material 910
may be provided on the interior of the tube 902. In the
illustrative embodiment of FIGS. 30A and 30B a 1.0 mm wide strip of
high friction tape 910 has been adhesively bonded to the interior
of the tube 902. A suitable material for use in this application is
a self-adhesive high friction tape available from 3M Manufacturing
Co., Inc. which is made of a polyurethane film with mineral
particles embedded in the exterior surface to enhance the
frictional properties. The high friction tape 910 is mounted in the
tube 902 with the high friction gripping surface oriented toward
the lumen 912 of the tube 902. When a suture 906 is tied around the
exterior of the frictional locking suture ring 900, the high
friction surface of the tape 910 is pressed against the exterior of
the catheter shaft 920 to increase the grip on the catheter.
[0169] Preferably, the frictional locking suture ring 900 is placed
over the catheter shaft from the distal end during manufacturing.
In use, the suture ring 900 initially resides in an out of the way
position at the proximal end of the catheter near the proximal hub
while the catheter 920 is being introduced and maneuvered into
position within the patient's aorta. Once the distal end of the
catheter has been maneuvered to the proper position, the catheter
920 can be secured in position by sliding the suture ring 900 along
the catheter shaft 920 until it is close to the introduction site.
A suture 906 is tied around exterior of the suture ring 900 to
create a frictional grip between the suture ring 900 and the
catheter shaft 920. The suture 906 is then stitched through the
patient's skin close to the insertion site and tied. This securely
fastens the catheter 920 in the desired position relative to the
patient's body with the correct length of catheter inserted into
the patient's vasculature. If preferred, separate sutures can be
used for tying the suture ring 900 and stitching it to the patient.
Alternatively, the suture ring 900 can be secured to the surgical
drapes covering the patient, though this is less preferred because
there can be relative movement between the drapes and the catheter
introduction site that could result in movement of the catheter
from its desired position.
[0170] If it becomes necessary to reposition the catheter 920 at
any time during the procedure, the frictional grip can be released
by untying or cutting the suture 906 around the suture ring 900.
The catheter 920 can be repositioned by sliding it through the
lumen 912 of the suture ring and then it can be secured in the new
position by retying the suture 906 around the suture ring 900. When
it is time to remove the catheter 920, the suture 906 fastening the
suture ring 900 to the patient can be cut and the suture ring 900
withdrawn with the catheter 920.
[0171] In a further aspect of the invention, illustrated in FIGS.
30-34, the endoaortic partitioning catheter 895 is coupled to an
arterial bypass cannula 850 that is specially adapted to serve as a
dual purpose arterial bypass cannula and introducer sheath so as to
allow the catheter 895 and the cannula 850 to be introduced through
the same arterial puncture. The smaller diameter endoaortic
partitioning catheters made possible by the embodiments described
in relation to FIGS. 5-9, are particularly suitable for use in
combination with the special arterial bypass cannula 850. The
arterial bypass cannula 850 is configured for connection to a
cardiopulmonary bypass system for delivering oxygenated blood to
the patient's arterial system. The arterial bypass cannula 850,
shown in FIG. 31, has a cannula body 851 which is preferably made
of a transparent, flexible, biocompatible polyurethane elastomer or
similar material. In one preferred embodiment, the cannula body 851
has a 45.degree. beveled distal end 853, a proximal end 852, a
blood flow lumen 857 extending between the proximal end 852 and the
distal end 853, and an outflow port 891 at the distal end 853.
Alternatively, the cannula body 851 can have a straight cut distal
end with chamfered or rounded edge. Optionally, a plurality of
additional outflow ports may be provided along the length of
cannula body 851, particularly near distal end 853. The cannula
body 851 is tapered from the proximal end 852 to the distal end 853
and, in one preferred embodiment, the tapered cannula body 851 is
reinforced with a coil of flat stainless steel wire 854 embedded in
the wall of the cannula body 851. Adjacent to the proximal end 852
of the cannula body 851, proximal to the reinforcing coil 851, is a
clamp site 851 which is a flexible section of the tubular cannula
body 851 that can be clamped with an external clamp, such as a
Vorse type tube occluding clamp, forming a hemostatic seal to
temporarily stop blood flow through the lumen 857 of the cannula
850. In a preferred embodiment, the cannula body 851 has a length
between about 10 cm and 60 cm, and preferably between about 12 cm
and 30 cm. In one particular embodiment, the cannula body 851 has a
distal external diameter of approximately 7 mm or 21 French
(Charrire scale) and a distal internal diameter of approximately
6.0 mm or 18 French. In a second particular embodiment, the cannula
body 851 has a distal external diameter of approximately 7.7 mm or
23 French (Charrire scale) and a distal internal diameter of
approximately 6.7 mm or 20 French. Preferably, the proximal end 852
of the cannula body 851 of either embodiment has an internal
diameter of approximately {fraction (3/8)} inch or 9.5 mm. The
choice of which embodiment of the arterial bypass cannula 850 to
use for a given patient will depend on the size of the patient and
the diameter of the artery chosen for the arterial cannulation
site. Generally, patients with a larger body mass will require a
higher infusion rate of oxygenated blood while on cardiopulmonary
bypass, therefore the larger arterial bypass cannula 850 should be
chosen if the size of the artery allows.
[0172] An adapter assembly 865 is connected to the proximal end 852
of the cannula body 851. In one preferred embodiment, the adapter
assembly 865 and the cannula body 851 are supplied preassembled as
a single, sterile, ready-to-use unit. Alternatively, the adapter
assembly 865 can be packaged and sold as a separate unit to be
connected to the cannula body 851 at the point of use. The adapter
assembly 865 has a Y-fitting 858 which is connected to the proximal
end 852 of the cannula body 851. The Y-fitting 858 has a first
branch ending in a barbed connector 859 which is configured for
fluid connection to tubing 892 from a cardiopulmonary bypass
system, as shown in FIG. 34. To prepare the arterial bypass cannula
850 for insertion into a peripheral artery, such as a patient's
femoral artery or brachial artery, by an arterial cutdown or by a
percutaneous Seldinger technique, a connector plug 871, which is
molded of a soft, elastomeric material, is placed over the barbed
connector 859. A tapered dilator 867 is passed through a wiper-type
hemostasis seal 872 in the connector plug 871. The wiper-type
hemostasis seal 872 is a hole through the elastomeric connector
plug 871 that has a slight interference fit with the external
diameter of the dilator 867. A series of ridges can be molded
within the hemostasis seal 872 to reduce the sliding friction on
the dilator 867 while maintaining a hemostatic seal. The dilator
867 has a tapered distal tip 869, a proximal hub 870 with a luer
lock connector, and a guidewire lumen 879, sized for an 0.038 inch
diameter guidewire, that runs from the distal tip 869 to the
proximal hub 870. The diameter of the dilator 867 is such that the
dilator 867 substantially fills the cannula lumen 857 at the distal
end 853 of the cannula body 851. The length of the dilator 867 is
such that the distal tip 869 of the dilator 867 extends
approximately 2 to 5 cm, and more preferably 4 to 5 cm, beyond the
beveled end 853 of the cannula body 851 when the dilator hub 870 is
against the connector plug 870. The dilator 867 may assume a bend
873 in it at the point where the dilator 867 passes through the
Y-fitting 858 when the dilator 867 is fully inserted. One or more
depth markers 874, 875 can be printed on the dilator 867 with a
nontoxic, biocompatible ink. One depth marker 874 may be placed so
that, when the marker 874 is just proximal to the hemostasis seal
872 on the elastomeric connector plug 871, the tapered distal tip
869 of the dilator 867 is just emerging from the beveled end 853 of
the cannula body 851. In one particular embodiment, the tapered
dilator 867 is made of extruded polyurethane with a radiopaque
filler so that the position of the dilator can be verified
fluoroscopically.
[0173] A second branch of the Y-fitting 858 is connected to an
extension tube 862 which terminates in a hemostasis valve 876
configured to receive the endoaortic partitioning catheter 895
therethrough. The extension tube 862 has a flexible middle section
which serves as a proximal clamp site 864 that can be clamped with
an external clamp, such as a Vorse type tube occluding clamp,
forming a hemostatic seal to temporarily stop blood flow through
the lumen 863 of the extension tube 862. The lumen 863 of the
extension tube 862 between the proximal clamp site 864 and the
hemostasis valve 876 serves as a catheter insertion chamber 866,
the function of which will be more fully explained in connection
with FIG. 33.
[0174] In a preferred embodiment of the arterial bypass cannula
850, the hemostasis valve 876 is a type of compression fitting
known in the industry as a Tuohy-Borst adapter. The Tuohy-Borst
adapter 876 is shown in greater detail in FIG. 32. The Tuohy-Borst
adapter 876 has a compressible tubular or ring-shaped elastomeric
seal 883 that fits within a counterbore 879 in the fitting body
877. The elastomeric seal 883 is preferably made from a soft,
resilient, self-lubricating elastomeric material, such as silicone
rubber having a hardness of approximately 20-50 and preferably
40-50 Shore A durometer. The elastomeric seal 883 has a central
passage 884 with a beveled entry 885 on the proximal end of the
passage 884. The elastomeric seal 883 has a beveled distal surface
886 angled at about 45.degree. which fits against a tapered seat
880 in the bottom of the counterbore 879 that is angled at about
60.degree.. A threaded compression cap 887 screws onto the fitting
body 877. The threaded cap 887 has a tubular extension 887 which
fits within the counterbore 879 in the fitting body 877. An
externally threaded section 888 on the proximal end of the tubular
extension 887 engages an internally threaded section 881 within the
proximal end of the counterbore 879. When the threaded cap 887 is
screwed down onto the fitting body 877, the tubular extension 889
bears on the elastomeric seal 883 forcing it against the tapered
seat 880 of the counterbore 879. The resultant force on the
elastomeric seal 883 squeezes the elastomeric seal 883 inward to
close off the passage central 884 to make a hemostatic seal. When
the threaded cap 887 is unscrewed again from the fitting body 877,
the central passage 884 of the elastomeric seal 883 opens up again.
The deliberate 15.degree. mismatch between the angle of the beveled
distal surface 886 of the elastomeric seal 883 and the tapered seat
880 of the counterbore 879 prevents the elastomeric seal 883 from
binding and causes the central passage 884 to open up reliably when
the threaded cap 887 is unscrewed from the fitting body 887. An
internal ridge 890 within the threaded cap 887 engages in a snap
fit with an external ridge 882 on the proximal end of the fitting
body 877 to keep the threaded cap 887 from being inadvertently
separated from the fitting body 877 if the threaded cap 887 is
unscrewed to the point where the threads 888, 881 are no longer
engaged.
[0175] In one particular embodiment, the central passage 884 of the
elastomeric seal 883 has an internal diameter of about 5 mm to
allow clearance for inserting a catheter 895 with a shaft diameter
of 3-4 mm through the Tuohy-Borst adapter 876 without damaging the
occlusion balloon 896 mounted on it. The Tuohy-Borst adapter 876 is
adjustable through a range of positions, including a fully open
position for inserting the balloon catheter 896, a partially closed
position for creating a sliding hemostatic seal against the shaft
897 of the catheter 895, and a completely closed position for
creating a hemostatic seal with no catheter in the central passage
884. In an alternative embodiment, the central passage 884 of the
elastomeric seal 883 can be sized to have a slight interference fit
with the shaft 897 of the catheter 895 when uncompressed. In this
embodiment, the Tuohy-Borst adapter 876 has positions which include
a fully open position for creating a sliding hemostatic seal
against the shaft 897 of the catheter 895, and a completely closed
position for creating a hemostatic seal with no catheter in the
central passage 884. In a second alternative embodiment, a separate
ring-like wiper seal (not shown) is added in series with the
Tuohy-Borst adapter 876 to create a passive sliding hemostatic seal
against the shaft 897 of the catheter 895 without the necessity of
tightening the threaded cap 887. Additionally, the Tuohy-Borst
adapter 876, in either embodiment, may have a tightly closed
position for securing the catheter shaft 897 with respect to the
patient. In other alternative embodiments, other known hemostasis
valves may be substituted for the Tuohy-Borst adapter 876 as just
described.
[0176] In a particularly preferred embodiment, the internal surface
of the lumen 863 of the extension tube 862 and/or the internal
surface of the lumen 857 of the cannula body 851 are coated with a
highly lubricious biocompatible coating, such as polyvinyl
pyrrolidone, to ease the passage of the endoaortic partitioning
catheter 895, and especially the occlusion balloon 896, through
these lumens. Other commercially available lubricious biocompatible
coatings can also be used, such as Photo-Link.TM. coating available
from BSI Surface Modification Services of Eden Prairie, Minn.;
sodium hyaluronate coating available from Biocoat of Fort
Washington, Pa.; proprietary silicone coatings available from TUA
of Sarasota, Fla.; and fluid silicone or silicon dispersions.
Similarly, a distal portion of the exterior of the cannula body 851
can be coated with one of these lubricious biocompatible coatings
to facilitate insertion of the arterial bypass cannula 850 into the
artery at the cannulation site. Furthermore, the endoaortic
partitioning catheter 895 itself, in any of the embodiments
described herein, can be coated with one of these lubricious
biocompatible coatings to facilitate its insertion and passage
through the arterial bypass cannula 850 and the patient's
vasculature. Preferably, the occlusion balloon 896 of the
endoaortic partitioning catheter 895 should be free of any
lubricious coating so that there is sufficient friction between the
expanded occlusion balloon and the interior aortic wall to prevent
accidental dislodgement or migration of the occlusion balloon
896.
[0177] In operation, the arterial bypass cannula 850 is prepared
for insertion as shown in FIG. 31, with the tapered dilator 867 in
place in the blood flow lumen 857 of the cannula body 851 and with
the Tuohy-Borst fitting 876 completely closed. An arterial cutdown
is made into an artery, preferably the patient's femoral artery, at
the cannulation site or a guidewire is placed percutaneously using
the Seldinger technique and the dilator 867 and the distal end 853
of the cannula body 851 are inserted into the lumen of the artery
with the bevel up. A suture 894 can be tied around the artery 893
where the cannula body 851, as shown in FIG. 33, inserts to avoid
bleeding from the artery 893 at the cannulation site. The dilator
867 is then withdrawn from the cannula body 851, allowing blood to
flash back and fill the lumen 857 of the cannula body 851. When the
tip 868 of the dilator 867 is proximal to the distal clamp site 856
an external clamp is applied to the distal clamp site 856 to stop
further blood flow. The dilator 867 is completely withdrawn and the
connector plug 871 is removed so that a tube 892 from the
cardiopulmonary bypass system can be attached to the barbed
connector 859 of the Y-fitting 858, as shown in FIG. 33. Air is
bled from the arterial bypass cannula 850 by elevating the
extension tube 862 and opening the Tuohy-Borst fitting 876 slightly
and releasing the external on the distal clamp site 856 to allow
the blood to flow out through the Tuohy-Borst fitting 876.
Alternatively, air can be bled out of the arterial bypass cannula
850, through an optional vent fitting with a luer cap (not shown)
that can be provided on the Y-fitting 858 or an infusion line and a
three-way stopcock. The optional vent fitting can be also used as a
port for monitoring perfusion pressure within the arterial bypass
cannula 850. Once the air is bled out of the system, the external
clamp can be removed from the distal clamp site 856 the
cardiopulmonary bypass system pump can be turned on to perfuse the
patient's arterial system with oxygenated blood at a rate of about
3 to 6 liters/minute, preferably at a pump pressure of less than
about 500 mmHg.
[0178] To introduce the endoaortic partitioning catheter 895 into
the arterial bypass cannula 850, an external clamp 891 is placed on
the proximal clamp site 864, as shown in FIG. 33, to stop blood
from flowing out through the extension tube 862 and the Tuohy-Borst
adapter 876 is opened all the way by unscrewing the threaded cap
887 to open up the passage 884 through the elastomeric seal 883.
The distal end of the endoaortic partitioning catheter 895 with the
occlusion balloon 896 mounted thereon is inserted through the
passage 884 of the Tuohy-Borst adapter 876 into the insertion
chamber 866 of the arterial bypass cannula 850. Optionally, first
and second depth markers 898, 899 may be printed on the shaft 897
of the endoaortic partitioning catheter 895 with a nontoxic,
biocompatible ink. The first depth marker 898 on the catheter 895
indicates when the occlusion balloon 896 is entirely distal to the
elastomeric seal 883. When the first depth marker 898 is positioned
just proximal to the threaded cap 887, the Tuohy-Borst adapter 876
should be tightened to create a sliding, hemostatic seal around the
catheter shaft 897. Now, the clamp 891 can be removed to allow the
catheter 895 to be advanced distally through the arterial bypass
cannula 850.
[0179] Before the endoaortic partitioning catheter 895 enters the
blood flow lumen 857 within the Y-fitting 858, the perfusion rate
from the cardiopulmonary bypass system pump should be temporarily
turned down to a rate of about 1 to 2 liters/minute to avoid
hemolysis, tubing disruptions or other complications due to the
additional flow resistance caused by the occlusion balloon 896 as
it passes through the blood flow lumen 857. The catheter 895 can
now be advanced distally until the occlusion balloon 986 is distal
to the distal end 853 of the cannula body 851. A second depth
marker 899 on the catheter 895 indicates when the occlusion balloon
896 is entirely distal to the distal end 853 of the cannula body
851. When the second depth marker 898 reaches the proximal end of
the threaded cap 887, as shown in FIG. 33, the perfusion rate from
the cardiopulmonary bypass system pump should be returned to a rate
of about 3 to 6 liters/minute. The endoaortic partitioning catheter
895 can now be advanced into the ascending aorta for partitioning
the heart and inducing cardioplegic arrest according to the methods
described above. When the endoaortic partitioning catheter 895 is
in position within the ascending aorta the Tuohy-Borst adapter 876
can be tightened around the catheter 895 to act as a friction lock
to hold the catheter in place.
[0180] After completion of the surgical procedure on the heart, the
endoaortic partitioning catheter 895 can be removed from the
arterial bypass cannula 850 by reversing the sequence of operations
described above. The arterial bypass cannula 850 can remain in
place until the patient has been weaned from cardiopulmonary
bypass, then the arterial bypass cannula 850 can be removed and the
arterial puncture site repaired.
[0181] It should be noted that for the venous side of the
cardiopulmonary bypass system, a similar dual purpose venous bypass
cannula and introducer sheath with the above-described features can
be used for accessing the femoral vein and for introducing a
venting catheter or other devices into the venous side of the
circulatory system. In a venous configuration the dual purpose
venous bypass cannula and introducer sheath preferably has an
external diameter of about 21 to 32 French units, an internal
diameter of about 18 to 30 French units, and a length of about 50
to 75 cm.
[0182] FIGS. 35A-35C illustrate another means of steering the
distal tip 171 of the endoaortic partitioning catheter 170 for
centering the catheter tip within the ascending aorta B. The
endoaortic partitioning catheter 170 is shown positioned within the
patient's aortic arch A in FIG. 35A. The distal tip 171 of the
catheter 170 is made steerable by a multichamber occlusion balloon
172 mounted on the distal portion 173 of the catheter which is
shown partially cut away in FIG. 35A. The distal portion 173 of the
catheter 170 has a distal curve which may be a
180.degree..+-.45.degree. arc or a 270.degree..+-.45.degree. arc,
as described in previous embodiments. The multichamber occlusion
balloon 172 has a first chamber 174 and a second chamber 175. The
balloon 172 is mounted so that the first chamber 174 is oriented
toward the outside of the distal curve and the second chamber 175
is oriented toward the inside of the distal curve. A first
inflation lumen 176 in the catheter 170 connects to the first
chamber 174 through a first inflation port 178. A second inflation
lumen 177 in the catheter 170 connects to the second chamber 175
through a second inflation port 179. An infusion lumen 181 connects
with one or more infusion ports 182 at the distal tip 171 of the
catheter 170.
[0183] As shown in the cross section of the deflated occlusion
balloon 172 in FIG. 35B, a partition wall 180 separates the first
174 and second 175 chambers of the balloon 172. The first 174 and
second 175 chambers of the balloon 172 may be differentially
inflated through the inflation lumens 176, 177. For example, the
cross section of FIG. 35C shows the first chamber 174 of the
multichamber occlusion lumen 172 inflated to a greater degree than
the second chamber 175. Because the first chamber 174 is oriented
toward the outside of the distal curve of the catheter 170, the
distal tip 171 of the catheter 170 is forced toward the inside of
the aortic arch A, that is, toward the left side of the patient, as
in FIG. 35A. Alternatively, the second chamber 175 can be inflated
to a greater degree than the first chamber 174 to force the distal
tip 171 of the catheter 170 toward the outside of the aortic arch
A, that is, toward the right side of the patient. Thus, the distal
tip 171 of the catheter 170 can be steered to center the tip 171
within the lumen of the ascending aorta B under fluoroscopic
observation by inflating and deflating the individual chambers of
the multichamber occlusion balloon 172. It should be noted that the
multichamber occlusion balloon 172 is not limited to only two
chambers. The multichamber occlusion balloon 172 can be made with
three, four or more chambers to give the distal tip 171 greater
degrees of steerability.
[0184] It should be noted that while several aspects of the present
invention have been illustrated and discussed separately in the
foregoing description, many of these aspects can be advantageously
combined into a single, multifunction embodiment. As an
illustrative example, FIG. 36 shows a multifunction embodiment of
the endoaortic partitioning catheter 960 combining several of the
inventive aspects previously discussed. The shaft 964 of the
catheter 960 has a coaxial construction with an inner 961 and outer
962 tubular member, similar to the embodiments described in
connection with FIGS. 5A-5D and 6A-6D. The catheter shaft 964 may
be made with varying degrees of stiffness along the length of the
shaft 964, culminating in a soft atraumatic tip 965 which may be
highly loaded with a radiopaque filler. The catheter shaft 964 may
be made with a precurved distal portion 966 similar to FIGS.
10A-10B, or with a precurved distal portion 966 which is out of
plane with the proximal portion of the catheter shaft 964, as in
FIGS. 11A-11B. An expandable occlusion balloon 963 is mounted on
the distal portion 966 of the catheter shaft 964. The occlusion
balloon 963 preferably has a low profile deflated state with an
ellipsoidal shape, similar to that shown in FIG. 6A. In addition,
the occlusion balloon 963 may have an eccentric or asymmetrical
inflated profile 963', similar to any of the embodiments discussed
in relation to FIGS. 14-26, or FIG. 35 which would also provide a
steering means for the distal tip of the catheter, as would the
steering mechanism of FIG. 27.
[0185] The occlusion balloon 963 is mounted with its distal balloon
neck 967 attached to the inner tubular member 961 and its proximal
balloon neck attached to the outer tubular member 962. The inner
tubular member 961 is attached at its proximal end to a first hub
971 and the outer tubular member 962 is attached at its proximal
end to a second 969 hub 971 which are axially slidably and/or
rotatable with respect to one another, similar to the embodiments
described in relation to FIGS. 8A-8D and 9A-9B. An infusion fitting
977, such as a luer lock, on the first hub 971 is connected to an
infusion lumen 978 which terminates at the distal end of the
catheter 960. An inflation fitting 970, preferably a luer lock, on
the second hub 971 is connected to an inflation lumen 979 defined
by an annular space between the inner 961 and outer 962 tubular
members which communicates with the interior of the occlusion
balloon 963.
[0186] The second hub 969 may be moved proximal and/or rotated with
respect to the first hub 971 to minimize the deflated profile of
the occlusion balloon 963. The lower deflated profile of the
occlusion balloon 963 facilitates easy insertion of the catheter
960 through a dual function arterial cannula and introducer sheath
850, similar to that described in relation to FIGS. 31-34. When the
endoaortic partitioning catheter 960 is combined with the dual
function arterial cannula and introducer sheath 850, the shaft 964
of the catheter 960 should be made with an additional 20-25 cm of
length for a total shaft length of approximately 100-115 cm. The
diameter of the catheter shaft 964 should also be minimized as much
as possible to reduce the amount of cross sectional area the
catheter shaft 964 takes up in the blood flow lumen of the arterial
cannula 850. To this end, this combined embodiment is made with a
distal pressure transducer 972 and a balloon pressure monitoring
transducer 973 mounted on the inner tubular member 961, as
described in relation to FIGS. 7A-7C. The distal pressure
transducer 972 and the balloon pressure monitoring transducer 973
are electrically connected to an electrical connector 974 on the
first hub 971. Also on the first hub 971 is a fiberoptic connector
976 which connects to a fiberoptic bundle 975 which terminates with
a means for directing a lateral beam of light at the distal end of
the catheter 960 for aortic transillumination and/or for
facilitating nonfluoroscopic placement of the catheter 960. The
fiberoptic bundle 975 may also be made as a separate unit for
insertion through the infusion lumen 978 of the catheter 960 to
further reduce the catheter shaft diameter while maintaining
maximum functionality. The diameter of the catheter shaft 964 can
thus be reduced to as small as 8 to 10.5 French (2.7-3.5 mm
diameter).
[0187] Additionally the endoaortic partitioning catheter 960 may be
combined with a frictional locking suture ring 900 for anchoring
the catheter 960 in the proper position after placement, as
described in relation to FIGS. 30A-30B.
[0188] Referring to FIG. 37, another preferred balloon 401 is shown
which includes surface features for reducing migration of the
balloon 401. The balloon 401 includes an outer surface having a
first, low-friction portion 403 and a second, high-friction portion
405. The second, high-friction portion 405 includes a number of
short ribs 407 and a selective coating 409 which enhance the
frictional engagement between the balloon 401 and the aortic lumen
relative to the frictional engagement between the first portion 403
and the aortic lumen. The selective coating 409 may be provided by
masking the first portion 403 and sandblasting the second portion
405. Alternatively, the method described in PCT/US94/09489 may be
used to provide the high friction portion 405. The balloon 401
preferably has a substantially oval cross-sectional shape tapered
in the distal and proximal directions, however, any balloon shape
may be used.
[0189] Referring to the end view of FIG. 38, the balloon 401
preferably includes at least three, and more preferably at least
four, arms 411 extending radially outward. A number of low-friction
portions 403 are positioned at radially-outward portions of the
arms 411. The high friction portions 405 are positioned between the
low friction portions 403 so that when the balloon passes through a
cylindrical body, such as a blood vessel, the low-friction portions
403 contact the vessel while the first, high-friction portions 405
do not. The balloon 401 is preferably evacuated prior to insertion
into the patient at which time it can be verified that the radially
extending arms 411 are present. Although it is preferred to provide
the radially-extending arms 411, the balloon 401 may be configured
in any other fashion so long as the low friction portions 403 are
at radially-outward positions relative to the exposed, high
friction portions 405.
[0190] The balloon 401 is preferably introduced through the
arterial bypass cannula 850 of FIGS. 31-36 although any other
delivery system may be used. In order to pass the balloon 401
through the arterial bypass cannula 850, the balloon 401 may be
temporarily folded or wrapped around the shaft so that the balloon
401 fits through the arterial bypass cannula 850. Once the balloon
401 passes through the arterial bypass cannula 850, the balloon 401
assumes the collapsed shape of FIG. 38 so that the low friction
portions 403, which are at the radially outward positions, engage
the body passageway. The balloon 401 is then advanced in the
patient to the desired location, such as the ascending aorta, and
the balloon 401 is inflated. Referring to FIG. 39, an end view of
the balloon 401 is shown with the balloon 401 in an inflated
condition. When the balloon 401 is expanded, the high friction
portions 405 evert and are exposed for anchoring the balloon 401.
Although it is preferred to provide the selective coating 409
and/or ribs 407, the first portion 403 may include any other
friction enhancing feature such as spiral ribs, knobs,
cross-hatching, or a fine mesh. Furthermore, the first and second
portions 403, 405 are preferably integrally formed, however, the
first and second portions 403, 405 may be fabricated separately and
attached to one another. The balloon 401 is mounted to a shaft 413
having an inflation lumen 415, an infusion lumen 417 and a pressure
lumen 419 which are used in the manner described above when
occluding the ascending aorta. The balloon 401 may, of course, be
used in conjunction with any other catheter design disclosed herein
or otherwise known to one of ordinary skill in the art.
[0191] Referring to FIGS. 40 and 41, another preferred balloon 401A
is shown wherein like reference numbers are used to represent
similar features disclosed in the embodiment of FIGS. 37-39. The
first portions 403A are also positioned at radially-outward
positions of radially-extending arms 411A. The second portions 405A
extend between the first portions 403A and include a plurality of
ribs 407A and a high friction portion 409. When the balloon 401A
expands, the second portions 405A evert so that the balloon 401A
assumes a substantially cylindrical cross-section as shown in FIG.
39 with the both the low friction portions 403A and high friction
portions 409 exposed.
[0192] Referring to FIG. 42, another preferred method of anchoring
the balloon is shown. A balloon 501 is positioned in the ascending
aorta with clamps 503 positioned on both sides of the balloon 501
for anchoring the balloon 501 in the aorta. Each clamp 503 is sized
to slightly compress the aorta so that the balloon 501 cannot pass
by the clamp 503 when the balloon 501 is inflated. Although it is
preferred to provide two clamps 503, a clamp 503 having two pairs
of jaws may also be used. Furthermore, although it is preferred to
provide clamp 503 on both sides of the balloon 501, a single clamp
503 may be used if migration in only one direction is a problem.
When using only one clamp 503 which prevents upstream migration of
the balloon, the catheter shaft may be tensioned to prevent
downstream migration. The clamps 503 may be used in conjunction any
of the occluding members described herein or with any other
conventional occluding member such as mechanically deployed
occluding members.
[0193] Referring to FIG. 43, a plan view of the clamp 503 is shown.
The clamp 503 may also be any of the clamps disclosed in pending
U.S. patent application Ser. No. ______ by inventors Donlon et al.,
filed Dec. 4, 1995, Attorney Docket No. TTC No. 14635-42/Heartport
No. 039-CP, which is incorporated herein by reference. The clamp
503 includes jaws 505, 507 pivotally coupled together at a pivot
509. The jaws 505, 507 are biased open by a spring 511 and are
locked using ratchet 513. As shown, the clamp 503 does not occlude
the aorta but merely blocks migration of the balloon 501. A
deploying mechanism (not shown) is used to deploy and retrieve the
clamp 503.
[0194] Referring to FIG. 44A, another preferred method of anchoring
an occluding member is shown. The occluding member is preferably a
balloon 501A having an hour-glass shape with the clamp 503
positioned around an indentation 515 for anchoring the balloon 501A
in both directions. The balloon 501A preferably includes an inner
wall 516 at the indentation 515. Referring to FIG. 44B, the inner
wall 516 has holes 517 therethrough for pressure communication
between both sides of the inner wall 516. The inner wall 516 is
preferably inelastic or at least less elastic than the balloon
material so that the cross-sectional shape of the balloon 501A at
the indentation remains substantially the same after the balloon
501A has been inflated. The clamp 501A is preferably sized to
slightly compress the balloon 501A. An advantage of the embodiment
of FIG. 44A is that the cooperation of the balloon 501A and clamp
503 requires less distention or compression of the aorta than would
otherwise be necessary when using only a clamp or balloon.
Minimizing the overall deflection of the aorta may advantageously
minimize plaque release.
[0195] Referring to FIG. 45, a partial cut-away of another valve
876A for use with the cannula 850 is shown. Similar reference
numbers are used to represent similar items presented in previously
described embodiments and discussion of the similar items is
omitted here. A shaft displacing mechanism is coupled to the valve
876A for displacing a catheter shaft positioned therein. As will be
discussed in further detail below, the shaft displacing mechanism
facilitates displacing the shaft so that the shaft engages the body
passageway for anchoring the shaft which, in turn, anchors the
occluding member. The shaft displacing mechanism can move in an
inward direction, defined by arrow 819, and an outward direction
opposite to the inward direction. The shaft displacing mechanism
may be used with any catheter and is particularly useful when used
in conjunction with the shafts described below in connection with
FIGS. 46-49.
[0196] Referring still to FIG. 45, a threaded coupling 831 couples
body 877A to the remainder of the cannula 850 which is described in
connection with FIGS. 31-36. The body 877A includes lips 833 which
engage slots 835 in the cannula 850. The lips 833 and slots 835
permit axial displacement of the body 877A but prevent rotation of
the body 877A when the threaded coupling 831 is rotated. An o-ring
837 seals a space between the body 877A and cannula 850 so that
fluid does not pass therebetween. The threaded coupling 831 has
threads which engage the body 877A so that rotation of the threaded
coupling 831 displaces the body 877A axially. In this manner, a
shaft (not shown) which is positioned within the delivery cannula
is displaced upon rotation of the coupling 831. The body 877A also
preferably includes first, second and third indicators 821, 823,
825 which are described in further detail below in connection with
operation of the displacement mechanism. A spring (not shown) may
also be provided to preload the shaft in the inward or outward
directions. A spring-loaded mechanism would preferably include a
displacement stop to limit displacement of the shaft if forces on
the shaft exceed the spring preload.
[0197] Referring now to FIGS. 45-49, operation of the delivery
cannula 850 and valve 876A is now described. The threaded coupling
831 is initially registered with the second, intermediate indicator
823 so that the threaded coupling 831 can be moved either inward or
outward. After the shaft 903 is inserted into the patient and the
occluding member 901 is positioned at the desired location, such as
the ascending aorta A, the occluding member 901 is expanded to
occlude the aorta as shown in FIG. 46. At this time, the pressure
forces in the aorta tend to force the occluding member 901 in the
upstream direction. To resist the pressure forces on the occluding
member 901, the threaded coupling 831 is rotated so that the shaft
903 is moved in the inward direction. The third indicator 825 helps
the user determine the desired displacement of the shaft 903 in the
inward direction. A preferred range for the predetermined
displacement is between 1 and 5 cm, and more preferably between 2
and 4 cm, from the second indicator 823. When the shaft is
displaced in the inward direction, a first portion 905 engages the
radially outward wall RO. The shaft 903, which now engages the
aortic lumen, anchors the occluding member 901 against upstream
migration. The shaft 903 and occluding member 901 are preferably
made of the same materials and have the same dimensions as the
embodiments described above in connection with FIGS. 10-30.
[0198] After cardiopulmonary bypass is established, the pressure
forces at this time tend to force the balloon in the downstream
direction. To resist these forces, the threaded coupling 831 is
rotated so that the shaft 903 moves in the outward direction. The
first indicator 821 provides a predetermined displacement in the
outward direction which is preferably between 1 and 6 cm, and more
preferably between 2 and 4 cm, relative to the second indicator
823. Referring to FIG. 47, a second portion 907 of the shaft 903
engages the radially inner wall RI of the aortic lumen. The second
portion 907 is preferably the radially inner wall of the
hook-shaped portion. Although it is preferred to provide the
indicators 821, 823, 825, the threaded coupling 831 and body 877A
may be sized so that the maximum displacements match the desired
displacements. Furthermore, although it is preferred to provide a
threaded displacement mechanism, any other conventional connection
may be used such as a bayonet connection, a ratchet and pawl, or a
slidable connection with a frictional lock.
[0199] Referring to FIGS. 48 and 49, another preferred catheter is
shown. The shaft 903A has a first portion 905A for engaging the
radially outer wall RO of the aortic lumen (FIG. 48) and a second
portion 907A for engaging the radially inner wall RI of the aortic
lumen (FIG. 49). A third portion 909A also engages the radially
outer wall RO to further resist balloon migration in the upstream
direction. The second and third portions 907A, 909A are positioned
at first and second bends 911A, 913A. The first bend 911A is
preferably between 3 and 12 cm, and more preferably between 5 and
10 cm, from the distal end 915A. A first substantially-straight
section 917A extends between the first and second bends and
preferably has a length between 3 and 12 cm, and more preferably
between 3 and 8 cm. A second, substantially-straight section 919A
extends from the second bend 909A toward the proximal end. Although
it is preferred to provide a straight section between the first and
second bends 911A, 913A, a curved portion may also be provided.
[0200] The embodiments of FIGS. 46-49 preferably include a
relatively stiff proximal section 919, 919A and a flexible distal
section 921, 921A connected to the proximal section. Referring to
FIGS. 46-47, the proximal section 919 is substantially straight and
the distal section 921 includes the hook-shaped portion. Referring
to FIGS. 48 and 49, the proximal section 919A preferably terminates
just before the first bend 909A in FIG. 48 while the distal section
921A includes the first and second bends 911A, 913A. The proximal
section 919, 919A limits migration of the balloon by limiting the
overall deflection of the proximal end of the catheter. The distal
section 921, 921A preferably has a lower stiffness than the
proximal section 919, 919A so that the distal section 921, 921A may
conform somewhat to the shape of the aortic arch. The distal
section 921, 921A preferably extends between 10 and 20 cm and more
preferably between 10 and 15 cm from the proximal portion to the
distal end 915A. The proximal section 919, 919A preferably extends
between 40 and 100 cm, and more preferably between 80-90 cm, from
the distal section 921, 921A toward the proximal end. The flexible
and distal sections 919, 919A, 921, 921A may be coupled together by
any conventional method or may be integrally formed with the distal
section 921, 921A being formed with a smaller, more flexible
cross-sectional shape than the proximal portion 919, 919A or with
the proximal section having reinforcing ribbon, wires and the like.
The first and second portions 905, 907 also preferably include a
frictional coating or surface to further enhance anchoring.
[0201] Referring again to FIG. 47, yet another method of anchoring
an occluding member in the ascending aorta is shown. An anchor 923,
which is preferably a perfusion catheter, is introduced into the
patient and advanced into the brachiocephalic artery. The anchor
923 is coupled to the cardiopulmonary bypass system (see FIG. 1)
for delivering oxygenated blood to the brachiocephalic artery
during cardiopulmonary bypass. The anchor 923 advantageously limits
migration of the occluding member 901 and ensures oxygenated blood
reaches the brachiocephalic artery. Thus, the occluding member 901
of FIG. 47 is anchored against downstream migration by engagement
between the second portion 907 and the radially inner portion RI of
the aortic arch and the occluding member 901 is anchored against
upstream migration by the anchor 923. The dotted line position of
the occluding member 901 illustrates brachiocephalic anchor 923
blocking upstream migration of the occluding member 901. Although
it is preferred to provide a separate anchor 923, the
brachiocephalic anchor may be coupled to the balloon catheter and
deployed therefrom. Furthermore, although it is preferred to use
the anchor 923 to prevent migration of the occluding member 901,
the brachiocephalic anchor may simply be a thin shaft which resists
migration of the occluding member while permitting an adequate flow
of oxygenated blood into the brachiocephalic artery.
[0202] The methods and devices described herein provide methods and
apparatus for anchoring an occluding member and a specific
application of the present invention is developed with respect to a
system for partitioning a patient's heart and coronary arteries
from the remainder of the arterial system. While the above is a
description of the invention, various alternatives, modifications
and equivalents may be used. For example, the balloon of FIGS.
37-41 may have any other shape so long as the low friction portions
are at radially outward positions relative to the high friction
portions, the pressure monitor and pressure sensors may be used
with any type of balloon or occluding member, and the catheter 903,
903A may have any shape so long as predetermined portions are
provided for engaging the radially inner and outer walls of the
aortic lumen. Therefore, the above description should not be taken
as limiting the scope of the invention, which is defined by the
appended claims.
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